Can someone please 'splain this to me?

[Damn True]

Nearly every major race series (F1, CART, IRL, NASCAR etc) runs modest sized wheels with rather high profile tires. With the exception of ALMS & GT racing which run 17"-18" wheels and low profile tires (though most appear to be in the 45 series range).

Why the difference?

Benefits / drawbacks of each in a racing environment?

Benefits / drawbacks of each in a street/track-day environment?

[IsheeM]

F1 uses such large profile tires because the tires actually act as the majority their damping and springs (i.e. the tire side wall deflects more than their suspension system displaces). This to some extent applies to all open wheel racecars because they have such a small range of suspension travel. I dont really know about NASCAR. I know in Speed WC they are required to run 18s. I dont really know if there is a minimum wheel rule in the ALMS but I am sure there is and it is 19. But for the most part low profile tires provide more cornering stiffness in the tires which is usually better for road racing. So maybe that is why, but who knows.

Michael

[79T/Aman]

NASCAR uses 15" wheels as per the rules to keep it "stock" as are flat tappet cams circa 1950's "stock" stock cars are heavy 3300-3400# and very heavy springs, and as in open wheel cars the tire acts as a damper.