From the rule book
http://www.lemans.org/sport/pages/re..._2004_gb.shtml
“LM”P1
13.2.1 - Width (maximum) : 16"
13.2.2 - Diameter (maximum) : 28.5"
“LM”P2
13.2.1 - Width (maximum) : 14"
13.2.2 - Diameter (maximum) : 28"
GTS
13.1.1 - Wheels :
a/ Width ……… 14" maximum
b/ Diameter…... 28" maximum
13.1.2 - Rims :
a/ Diameter …….. 18" maximum
GT
Up to 1200 kg
a/ Maximum width : 12"
b/ Maximum diameter : 28"
over 1200 kg
a/ Maximum width : 14"
b/ Maximum diameter : 28"