A case to go back to smaller wheels and tyres

[bjohnsonsmith]

Originally Posted by Sodemo

I dont agree with cars being made narrower. Typically, narrower cars = less drag, which if you want organic "non DRS" passing - isnt always a good thing.

One step forward, two steps back.

I thought most F1 fans wanted to DRS to go.

[V8 Fireworks]

Originally Posted by Taxi645

https://www.motorsport.com/f1/news/f...ight/10528768/

"F1 could ditch 18-inch wheels for 2026 in bid to drop car weight"

"Perhaps a better way, which is being evaluated, would be to change tyre size entirely and move away from the 18-inch wheels that have been a part of F1 for the ground effect era."

Your 15" or 16 rim idea is excellent.

If the rims were to be downsized though, should the rear tyres remain at the existing 720mm diameter x 400mm section width -- similar to 16" wide x 28.5" diameter rear tyres used in Champcar USAC racing below -- or should they also be downsized to F2 or F1 circa 1998-2016 325mm rear section widths (with 660mm / 26" diameter)?



I don't understand the suggestion that a two wheel drive car with 1000hp does not need 400mm wide rear tyres myself. Surely it does need them?

While the 00's F1 cars did OK with modest 325mm section rear tyres, surely 400mm section is better?!

Going to a narrower car width than 2000mm, as per the above car and current F1 cars, would also lose the lovely Champcar-like proportions the current F1 cars have.

Go to a 15" rim and a narrower and smaller diameter front tyre (only), rear tyres the same size, that's all you need surely? Keep the same car width? Lovely Champcar magic in F1!

After all, compare the above to:


Not only is the car comically narrow, the rear tyres are comically narrow too.

Looks like a glorified World Series by Renault junior formula car. Fans got used to it, but it doesn't mean it was right in terms of the golden ratio et cetera.

Look at those long and elegant front wishbones on the Panoz, compare to the short & stubby goofy-looking ones on the Renault.

[Sodemo]

Originally Posted by bjohnsonsmith

I thought most F1 fans wanted to DRS to go.

I do! Why, did something I typed suggest that I don't?

[bjohnsonsmith]

Originally Posted by Sodemo

I do! Why, did something I typed suggest that I don't?

Maybe I misunderstood but in your post #200, you say narrower cars = less drag, which if you want organic "non DRS" passing - isnt always a good thing.

Surely, If you don't like DRS, and you want "non DRS" passing, then narrower cars are a good thing?

[Sodemo]

Originally Posted by bjohnsonsmith

Maybe I misunderstood but in your post #200, you say narrower cars = less drag, which if you want organic "non DRS" passing - isnt always a good thing.

Surely, If you don't like DRS, and you want "non DRS" passing, then narrower cars are a good thing?

Nope, because narrower cars = less drag, and if you want good racing, racing like people drafting on the straights and passing into corners, then I believe you would want more drag. If you think back to the 1998 tech changes, they sound like they are repeating all the same mistakes, narrower cars, grooved tyres etc. All that did in 98 was enable teams to run more aero due to the lower drag figures and resulted in cars that found it harder to follow and low speed handling that was problematic.

[bjohnsonsmith]

Originally Posted by Sodemo

Nope, because narrower cars = less drag, and if you want good racing, racing like people drafting on the straights and passing into corners, then I believe you would want more drag. If you think back to the 1998 tech changes, they sound like they are repeating all the same mistakes, narrower cars, grooved tyres etc. All that did in 98 was enable teams to run more aero due to the lower drag figures and resulted in cars that found it harder to follow and low speed handling that was problematic.

I thought more drag increased the wake, which makes it harder for the car that's following to get closer to the car in front. Wasn't that the reason for the new ground effect formula?

[Richard C]

Originally Posted by bjohnsonsmith

I thought more drag increased the wake, which makes it harder for the car that's following to get closer to the car in front. Wasn't that the reason for the new ground effect formula?

Complex topic.

I think it is the characteristics of the prior generation aero that resulting in particularly turbulent air behind the cars. I think the current spec was as much about changing the shape of the turbulent flow to make it less impactful of cars behind. For example it is not just the underbody wing. The mandated aero over the front wheel is an example of them looking to condition the wake in a specific way. I don't think it was about "reducing drag".

I broadly think a large part of the NEW effort to reduce drag is to more about ensuring the new cars can maintain similar speeds while using a PU that is likely to be less capable than the current generation. Simulations of a potential 2026 PU in the current cars was showing them having to lift and coast or slow on long straights. This fear was addressed by those working on the 2026 regulations by calling out that the 2026+ cars would have a technical spec that would result in less drag. Most likely by reducing the frontal area (narrower car, narrower tires, etc.) and maybe even active aero to reduce drag at high speed.

Richard.

[Richard C]

Originally Posted by Richard C

while using a PU that is likely to be less capable than the current generation.

Wants to provide some extra context on this. As always the power unit regulations are very complex. But a few key points...

* Revised (lower) flow rates which effectively drop power from the ICE by about 33%
* Energy storage in the batter is the same (I have been wrong by saying things like "bigger battery pack" is adding weight. It's probably other stuff such as the MGU-K)
* Increase in the rate of power that can be recovered or deployed by MGU-K
* Overall power is about the same, but at peak power, less is from the ICE and more from the electric motor.

Watch the following video at about 7min 40sec. It goes into where if you are dumping power out of the battery, given the higher power flow rates, you will deplete the battery much faster. So you can run out of "power" before the end of long straights. Video provides specifics.

https://www.youtube.com/watch?v=KxDQBVzXWt4

The entire video is very good and talks about many differences from a power generation, recovery and application for the current vs. next gen power units.

Apologies as this appears somewhat off topic, but it speaks as to why they want to reduce drag, because with less drag, it takes less power to maintain high speeds on straight. And all of this is about not having the cars be slower than current.

Richard

[Adam43]

Thanks. I've not been following what's going on here and it gives more context to my query and wonder in the Future Rule changes thread.

[Taxi645]

Originally Posted by V8 Fireworks

Your 15" or 16 rim idea is excellent.

If the rims were to be downsized though, should the rear tyres remain at the existing 720mm diameter x 400mm section width -- similar to 16" wide x 28.5" diameter rear tyres used in Champcar USAC racing below -- or should they also be downsized to F2 or F1 circa 1998-2016 325mm rear section widths (with 660mm / 26" diameter)?



I don't understand the suggestion that a two wheel drive car with 1000hp does not need 400mm wide rear tyres myself. Surely it does need them?

While the 00's F1 cars did OK with modest 325mm section rear tyres, surely 400mm section is better?!

Going to a narrower car width than 2000mm, as per the above car and current F1 cars, would also lose the lovely Champcar-like proportions the current F1 cars have.

Go to a 15" rim and a narrower and smaller diameter front tyre (only), rear tyres the same size, that's all you need surely? Keep the same car width? Lovely Champcar magic in F1!

After all, compare the above to:


Not only is the car comically narrow, the rear tyres are comically narrow too.

Looks like a glorified World Series by Renault junior formula car. Fans got used to it, but it doesn't mean it was right in terms of the golden ratio et cetera.

Look at those long and elegant front wishbones on the Panoz, compare to the short & stubby goofy-looking ones on the Renault.

Nice shots to illustrate the different proportions! I totally agree that the Champcar proportions look so much better.

On page 5 of this thread a posted an image of a Super Formula car (lowered the rear wing a bit as well to make the car look wider) with the wheels and tyres photoshopped to run the following spec:
270/645/R15 / R: 370/645/R15:



To me those rears look plenty wide. Why? Because the diameter is not crazy like it is now and it fit's with the general proportions of the car. Accidentally Super Formula cars are 1.9m wide, the width also proposed for 2026 F1. The wheel base of the SF are a tiny bit shorter still though at 3,115 mm.

If you want to work on efficiency (drag mainly) and weight in open wheel cars (like F1 does for 2026) then large wheel diameters tyres are a big enemy.




On the subject of how wide the tyres need to be in relation to the power output. If you get the weight and the drag down (F1 cars are insanely draggy, they are the opposite of state of the art in that regard), you don't need that much horsepower to produce the same lap time (and get a better handling car as well). Less power, matches with a slightly reduced width. Also keep in mind that the grooved rear tyres also only had the equivalent of a 330mm width tyre while still producing up to 900bhp at a certain point. There is quite a bit of margin there. Also consider the width aspect in relation to the whole spray discussion we had before. Furthermore, if you narrow the car, but keep the tyre width the same, you are moving the tyres spray closer to the ground effect area of the car leading to more problems with visibility.




BTW, in the past Bridgestone proposed to align tyre specs of the different open wheel classes across the world. As said before, if they decide to move to smaller wheels and tyres again in 2026 that could still be a good idea. To me that makes more sense then trying to align it with prototype classes (like they tried to do with the 18-inch wheels we have now) due to the different demands and aerodynamic consequences.

[Taxi645]

I had to look up the exact Champ car tyre specs. I found the following:

Front:
255/660/15

Rear:
370/710/15

So pretty close to what I'm proposing. Just that the Champ car tyres are slightly larger diameter (especially the rear) with a slightly higher tyre wall with more suspension in the tyre itself. Not F1 13-inch era levels of suspension though.

[Sodemo]

In terms of visual appeal, for me the best looking modern-ish single seaters were the Formula Renault 3.5 cars from the early 2000s.

[Taxi645]

Originally Posted by V8 Fireworks

Your 15" or 16 rim idea is excellent.

If the rims were to be downsized though, should the rear tyres remain at the existing 720mm diameter x 400mm section width -- similar to 16" wide x 28.5" diameter rear tyres used in Champcar USAC racing below -- or should they also be downsized to F2 or F1 circa 1998-2016 325mm rear section widths (with 660mm / 26" diameter)?



I don't understand the suggestion that a two wheel drive car with 1000hp does not need 400mm wide rear tyres myself. Surely it does need them?

While the 00's F1 cars did OK with modest 325mm section rear tyres, surely 400mm section is better?!

Going to a narrower car width than 2000mm, as per the above car and current F1 cars, would also lose the lovely Champcar-like proportions the current F1 cars have.

Go to a 15" rim and a narrower and smaller diameter front tyre (only), rear tyres the same size, that's all you need surely? Keep the same car width? Lovely Champcar magic in F1!

After all, compare the above to:


Not only is the car comically narrow, the rear tyres are comically narrow too.

Looks like a glorified World Series by Renault junior formula car. Fans got used to it, but it doesn't mean it was right in terms of the golden ratio et cetera.

Look at those long and elegant front wishbones on the Panoz, compare to the short & stubby goofy-looking ones on the Renault.

So I wanted to show a something based on the images you shared. So the dimensions of the below tyres is:



Front: 255/660/15, Rear: 370/710/15



On the right; Front: 255/635/13, Rear: 380/660/13



You can see that the front tyre is clearly a lot narrower (and smaller diameter in both cases) than the rear. I quite like that from the look side of things and it also helps to keep the weight and drag down, improve visibility and keeps the spray a bit further away from the under side (something that is especially welcome if you narrow the car like they are planning to do). I don't know how much scope there is to get the aero and weight balance such for 2026 to allow those narrower fronts again without creating too much understeer balance.

As said before, note how the rear tyre of the historic Ferrari actually looks wider due to the limited diameter. The front tyres of the current cars look bizarrely unlogically huge to me when you see it next to the other two.

Personally I would like sub 700kg cars with the following tyre size:

Front: 245/645/15, rear: 360/645/15

But I suspect we will end up with something like:

Front: 255/670/16, rear: 370/670/16


This in my book would still be a mayor improvement compared to the current tyres in almost every sense, optics, weight, drag, visibility, wet weather.

They could even combine the smaller diameter 15" with the bigger diameter 16'' in the rear like the 80's and champcar had, but I suspect they won't go for that.

[Taxi645]

Some more confirmation that we are probably moving to smaller dimensions:
https://www.motorsport.com/f1/news/p...2026/10546139/

"Formula 1 tyre manufacturer Pirelli expects to return to constructing smaller and lighter tyres for the new 2026 regulations as the FIA seeks to reduce car weight."

[Sodemo]

If there is a concern about spray in wet conditions, why not simply specify a wet tyre that is narrower but the dry tyre can be wider? In fact I’m pretty sure in the Bridgestone days that’s exactly what they did, the monsoon tyres were narrower, but had a much deeper tread.

[Taxi645]

Originally Posted by Sodemo

If there is a concern about spray in wet conditions, why not simply specify a wet tyre that is narrower but the dry tyre can be wider? In fact I’m pretty sure in the Bridgestone days that’s exactly what they did, the monsoon tyres were narrower, but had a much deeper tread.

I've suggested something like that earlier in the thread. I don't know how much scope there is to move to a narrower rim while maintaining the same hub en brake system. Apart from the quantity of spray, it would also help to keep the spray further away from the turbulent underside of the car.

[V8 Fireworks]

Originally Posted by Taxi645

But I suspect we will end up with something like:

Front: 255/670/16, rear: 370/670/16

It seems you are on the money. Well called!

One way that the slimming down of F1 car weight could be helped a lot would be the move to smaller tyres, with it understood that the 16-inch wheels are being seriously considered.

https://www.motorsport.com/f1/news/f...ight/10528768/

Also:

There is talk of the wheelbase being trimmed back by 20cm (from 3600mm to 3400mm), with the width being reduced by 10cm (from 2000mm to 1900mm). This would still be wider than the narrow cars of 2016 which were just 1800mm wide.

This (GP2-sized F1 cars) seems a sensible compromise.

It seems the front overhang will also be significantly shortened.

A render proposed by the FIA:

[Taxi645]

Originally Posted by V8 Fireworks

It seems you are on the money. Well called!


https://www.motorsport.com/f1/news/f...ight/10528768/

Also:

This (GP2-sized F1 cars) seems a sensible compromise.

It seems the front overhang will also be significantly shortened.

A render proposed by the FIA:

I'm not sure if it's an official FIA render or rather a auto-motor-und-sport render based on what was shared with the press up to this point:
https://www.auto-motor-und-sport.de/...echnik-bilder/


I did some measurements on that render and it seems the AMS render shows tires of roughly the following width:
Front: 270mm
Rear: 325mm


I think they are more AMS/the render artists guesses rather that the official width's. I hope we could see the fronts a bit narrower and the rear a bit wider. Weight and aero wise that would be close to a wash but it would look better in my view. As said before, not sure if they can get the aero and weight balance such to allow such a distribution.


I adjusted the rendering to make the widths as follows:
Front: 245mm
Rear: 350mm


To me that looks better. Here's a GIF that show's the adjustment:

[Sodemo]

For what reason have they done away with the forward rear wing end fences? Aren't they conducive to providing stable airflow to the rear wing? Without them, isn't the airflow more disturbed as it can hit the wing from a variety of angles?

[Taxi645]

Originally Posted by Sodemo

For what reason have they done away with the forward rear wing end fences? Aren't they conducive to providing stable airflow to the rear wing? Without them, isn't the airflow more disturbed as it can hit the wing from a variety of angles?

AKAIK, the wing end plates are changed to provide an inwash airflow. Apparently this provides cleaner airflow to the following car and makes it easier to follow other cars.

[Sodemo]

Brundle just said that the 2023 cars have 5 tons of downforce, so that’s 5000kg? I mean… that’s amazing, but I’d also say that’s ridiculous and totally unnecessary.

[V8 Fireworks]

FOM and FIA to abandon 16" wheel plan for 2026, Pirelli opposes the change to 16" and insists to stick with 18":
https://www.autosport.com/f1/news/f1...2026/10587733/

Oh well, that's a shame.

Instead they will just go down in the width of the tyre (probably to F2 sizes: 245mm section front, 325mm section rear, down from 305mm & 405mm respectively in F1) and down in the profile of the tyre (probably to 680-690mm overall diameter, down from 705mm in F2 currently and 725mm in F1 currently).

Originally Posted by Sodemo

that’s amazing, but I’d also say that’s ridiculous and totally unnecessary.

It makes them go fast, what's wrong with going fast?

F2 and Indycar cornering at 3.5G is very leisurely compared to F1 5.5G cornering.

People want to see F1 cars as something special, something apart from lesser categories no? Hence the 1000hp and the 5.5G.

By all means 650-700hp & 3.5G & 750-800kg of a F2 or Indycar is not "slow" in itself compared to 1000hp & 5.5G & 800kg of F1, but people like that extra 12 seconds per lap of Formula One! It makes for a greater spectacle.

As for the tyres, 405mm rears like current or going down to 325mm like F2, as I understand doesn't make that much difference to grip in itself. More about the temperature management and so on, you still get the grip from the multiplying effect of the downforce on normal force on the tyre.

Note: F2 minimum weight this year (with the updates to 2024 F1 safety standards of the new F2 chassis) is 795kg, more or less the same as F1 (798kg), despite smaller cars with narrower tyres...

The plan to reduce track width from 2000mm to 1900mm like F2 is still on, likewise the plan to reduce car length by 200-300mm. So the 2026 F1 cars should be close in overall size, proportions and tyre size to a current F2 car. As we see with 800kg F2 cars, this does not guarantee a lightweight car in and of itself when sticking to strict 2024 crash regulations (which no doubt be even stricter and more severe by 2026!).

[Taxi645]

Originally Posted by V8 Fireworks

FOM and FIA to abandon 16" wheel plan for 2026, Pirelli opposes the change to 16" and insists to stick with 18":
https://www.autosport.com/f1/news/f1...2026/10587733/

Oh well, that's a shame.

Instead they will just go down in the width of the tyre (probably to F2 sizes: 245mm section front, 325mm section rear, down from 305mm & 405mm respectively in F1) and down in the profile of the tyre (probably to 680-690mm overall diameter, down from 705mm in F2 currently and 725mm in F1 currently).




It makes them go fast, what's wrong with going fast?

F2 and Indycar cornering at 3.5G is very leisurely compared to F1 5.5G cornering.

People want to see F1 cars as something special, something apart from lesser categories no? Hence the 1000hp and the 5.5G.

By all means 650-700hp & 3.5G & 750-800kg of a F2 or Indycar is not "slow" in itself compared to 1000hp & 5.5G & 800kg of F1, but people like that extra 12 seconds per lap of Formula One! It makes for a greater spectacle.

As for the tyres, 405mm rears like current or going down to 325mm like F2, as I understand doesn't make that much difference to grip in itself. More about the temperature management and so on, you still get the grip from the multiplying effect of the downforce on normal force on the tyre.

Note: F2 minimum weight this year (with the updates to 2024 F1 safety standards of the new F2 chassis) is 795kg, more or less the same as F1 (798kg), despite smaller cars with narrower tyres...

The plan to reduce track width from 2000mm to 1900mm like F2 is still on, likewise the plan to reduce car length by 200-300mm. So the 2026 F1 cars should be close in overall size, proportions and tyre size to a current F2 car. As we see with 800kg F2 cars, this does not guarantee a lightweight car in and of itself when sticking to strict 2024 crash regulations (which no doubt be even stricter and more severe by 2026!).

From that article:
The smaller rim size was under consideration largely as part of ongoing efforts by the FIA to reduce the overall weight of the 2026 cars.

However, the change was opposed by Pirelli both for reasons of practicality and because of the potential marketing impact. I'm quite sure that they didn't switch from 13'' to 18" for practicality reasons so that leaves marketing as the only reason to go to 18''. Just as I have said before in this thread.

I have to admit I'm loosing interest in F1. Marketing over the core interests of the sport itself. The whole backstabbing and hand wrenching around the Red Bull sage. I would like to follow a sport, if I would enjoy nasty politics or marketing I would watch house of cards or or watch commercials.

[V8 Fireworks]

Originally Posted by Taxi645

However, the change was opposed by Pirelli both for reasons of practicality and because of the potential marketing impact. I'm quite sure that they didn't switch from 13'' to 18" for practicality reasons so that leaves marketing as the only reason to go to 18''. Just as I have said before in this thread.

Most racing categories use 18" tyres, so that does make sense.

What puzzles me is, if lighter smaller diameter wheels with higher profile tyres are faster, when given a free choice (the only rule being overall maximum diameter) why did ALL the Super Touring teams immediately go to the largest possible 19" wheels?



So that suggests wheel weight is not that important? After all, many F1 teams were using 15" wheels with relatively low profile tyres, before 13" wheels were made mandatory and eventually Bridgestone decided to make front tyres the same diameter as the rear (now the case from 1997 to the present day).

For example, here you can see the low profile 13" fronts and relatively lower profile 15" rears on the older Grand Prix car, in stark contrast to the very high profile 13" tyres front & rear mandated for the 1990's Grand Prix car:


If lower profile tyres on 15" rears were slower than high profile tyres on 13" rears and lower profile front tyres were slower than high profile ones, why would March specify them?! The profile of the fronts is also not far from current F1 cars either (obviously the profile will be reduced more in 2026).

The Super Touring and F1 examples tend to suggest that, overall on balance of unsprung rotational mass, tyre weight, sidewall deflection, kinematics, tyre contribution to wheel rate (undamped, uncontrolled wheel rate which is bad), the low profile tyres & heavier wheels are not slower (at least not for a circuit car, unlike a drag racing car where there is huge deflection of the rear tyre).

For pure inertia-dominated straight line acceleration the smaller wheels + high profile tyres are faster, and for wet conditions the high profile tyres that deflect more are faster BUT overall for a circuit racing lap in the dry, it seems the way the stiff short sidewalls better manages cornering forces may actually be faster despite the greater rotational inertia (testing by the likes of Tyre Reviews' Jonathon Benson backs this up for road cars, 17" fastest in the wet, 19" fastest in the dry).

Originally Posted by Taxi645

Marketing over the core interests of the sport itself.

I don't think it is clear cut that 18" low profile tyres are slower than 16" or 13" higher profiles on a dry circuit, even with the extra 25kg of rotational mass.

Why can it not be performance as well as marketing?

[Taxi645]

Originally Posted by V8 Fireworks

Most racing categories use 18" tyres, so that does make sense.

What puzzles me is, if lighter smaller diameter wheels with higher profile tyres are faster, when given a free choice (the only rule being overall maximum diameter) why did ALL the Super Touring teams immediately go to the largest possible 19" wheels?



So that suggests wheel weight is not that important? After all, many F1 teams were using 15" wheels with relatively low profile tyres, before 13" wheels were made mandatory and eventually Bridgestone decided to make front tyres the same diameter as the rear (now the case from 1997 to the present day).

For example, here you can see the low profile 13" fronts and relatively lower profile 15" rears on the older Grand Prix car, in stark contrast to the very high profile 13" tyres front & rear mandated for the 1990's Grand Prix car:


If lower profile tyres on 15" rears were slower than high profile tyres on 13" rears and lower profile front tyres were slower than high profile ones, why would March specify them?! The profile of the fronts is also not far from current F1 cars either (obviously the profile will be reduced more in 2026).

The Super Touring and F1 examples tend to suggest that, overall on balance of unsprung rotational mass, tyre weight, sidewall deflection, kinematics, tyre contribution to wheel rate (undamped, uncontrolled wheel rate which is bad), the low profile tyres & heavier wheels are not slower (at least not for a circuit car, unlike a drag racing car where there is huge deflection of the rear tyre).

For pure inertia-dominated straight line acceleration the smaller wheels + high profile tyres are faster, and for wet conditions the high profile tyres that deflect more are faster BUT overall for a circuit racing lap in the dry, it seems the way the stiff short sidewalls better manages cornering forces may actually be faster despite the greater rotational inertia (testing by the likes of Tyre Reviews' Jonathon Benson backs this up for road cars, 17" fastest in the wet, 19" fastest in the dry).




I don't think it is clear cut that 18" low profile tyres are slower than 16" or 13" higher profiles on a dry circuit, even with the extra 25kg of rotational mass.

Why can it not be performance as well as marketing?

With open wheel formula's drag becomes part of the equation much more than in touring classes. Especially now that they are focussing so much on efficiency. Sure one can reduce the tire height to get the same effect. I do think the drivers will love the effect that will have on their spines with the current and 2026 cars being already extremely stiff to keep the underside in the optimum flow regime. We can already predict the media topics, start 2026 seasons: "Drivers complain ride comfort is unacceptable in new generation cars".



https://www.motorsport.com/f1/news/n...sues/10588284/


And this is still with the current much higher tire height than what Pirelli is proposing for 2026.