JML

yes... specially when going above 19"wheels.
for circuit racing you get benefitted from larger wheels because you make a stiffer ride with big wheels, but you can compensate it raising the tire pressure.

Birdieman4

Anytime you go with an overall smaller circumferance setup (wheel & tire), you are effectivly shortening your gear ratio. If you had 20's on a stang and went to 16's (with a similarly sized tire), it would effectivly shorten your gear ratio, quite noticably.

Driver72

No not always, actually it can be the opposite.

It depends on weight and size mostly.

You can get 18" wheels/tires that weigh less than the stock 17's and are
a bit shorter by getting them slightly wider.
Doing that gives you a smaller side wall.

So you have a lighter, shorter tire/wheel combo that is wider for better traction
AND therefore better handling and braking!!

But 95% of the time you can only get away with this by upsizing only 1 size.
Going for the "bling" factor will without a doubt make you slower, as well as make
your car ride rougher, handle worse, and put unneeded stress on ball joints, brakes, etc
due to the added weight and rotational mass.

The stock 18" that Ford offers on the MGT was done wrong in my opinion.
They choose a wheel that's heavier and a tire that's heavier.
Will the 18" wheel/tire combo make the car handle better...yeah, it's got a shorter
sidewall so it won't flex as much. And the BFG's probably do have a bit better traction so
that will offset the weight increase to a degree when launching, but when
rolling the engine still has to turn that additional weight so it will slow progress....maybe another
reason why the LimeStang doesn't lose traction in third.

As an $895 option, Ford should of made sure the 18" wheels weighed about the same
or only slightly more than the 17's and they certainly should of put tires on that
were not only far superior, but weighed less than the 17" Pirelli's too.
THEN it would of been worth the money.

W1ldcat

Is a few pounds of tire weight that important. I weigh 170 and don't look at a 200lb driver and think I have an advantage because I weigh 30 pounds less. Not being a wise guy, but trying to learn something here.

viking396

Acutally you should look at that as an advantage. I'm 275lbs, drivng the same car you should win by a tenth just by that alone, having smaller wheels with better tires helps a tab bit more, look at everything because it all makes a difference, even if it's small.