Let's say you've got a well-balanced, RWD racecar that (for a variety of reasons) is limited to a 15x7" wheel. The car weighs 2800 lbs wet. You can fit 225 mm tires under the fenders. Should you?
In other words, should I stick with 205/50-15 tires (better fit on the wheel) or squeeze on some 225/45-15 rubber? Will the pinched-in sidewalls and potentially distorted contact patch negate any extra grip from the additional ~1 inch of tread width?
The tires in question would be either Hoosier R7 or Hankook Z214.
I've run 235/60 on 15x7 for years with no ill effects. But that is in muscle car land.
Look at how many ES miatas ran 225 tires on 6" rims and won all the time. Sure the 8" or 9" rim would be more square but I wouldn't pass up more rubber all day long.
moxnix
HalfDork
9/1/16 10:40 p.m.
Track or autox?
How much power?
I had 245 Hoosier a7s mounted on 16x6.5 wheels for the challenge. (I already had the tires).
One thing I notice is that the Hoosier+wheel is like 2x the weight of a stock wheel+ tire.... not good.
I'm still gonna run em, but crap they are heavy. Might be worth paying a bit of attention to the weight.
daeman
HalfDork
9/1/16 11:56 p.m.
I've got 215/50r18 hankook ventus v12's on 18x6jj Mitsubishi Pajero rims. They look alright and have been on for 2 years with no Ill effects. They seem to be wearing evenly and I don't feel much sidewall flex.
moxnix wrote:
Track or autox?
How much power?
Track only (vintage racecar). Power is about 200 hp.
With tires at that level, usually the sidewalls are stiff enough that even with a bit of pinch, the extra rubber will help you, as the sidewalls don't allow enough flex / rollover to waste the extra contact patch.
You will give up a little steering response and feel with the tires pinched, but depending on the car and driver, that's not necessarily a big deal.
I've done 275 Hoosiers on a 15x7.5 wheel. It is a bit pinchy, a 225 on a 7 really should be fine, Hoosier construction does well with a narrower wheel.
Hoosier sidewalls != street tire sidewalls.
