The "real life" difference between the two on the WRX is neglegible. You could argue that a 225 width tire fits better on a 7.5 and a 215 fits better on a 7, but the truth is they both work fine on either. The difference in handling/ride comfort could only be measured on very sensitive equipment. The rim you choose between the two should be by:

1. Fitment on your car (with low offset, the 7 might be better on wagons)
2. Quality
3. Weight
4. Look
5-9. other things
10. 7" vs. 7.5" argument

If you're a normal to moderately aggressive driver and the above answer satisfies you, don't read on.

The "sensitive equipment" would measure:

1. A bit less responsiveness on a narrower wheel because of the different sidewall angle that doesn't optimize the sidewall construction for responsiveness
2. A bit smoother ride on the narrower wheel for the same reason as above
3. A bit less overall traction on a narrower wheel because of the increased tire flex/deformation allowed
4. A bit more shoulder wear with aggressive driving on the narrower wheel because of the flex/deformation allowed

Again, those four points are just food for thought. The differences noticed by normal and moderately serious drivers are less than minute (mine-yoot).

 

Isn't there a point where you lose traction with wider wheels? Or is this more of a problem in snow where there is more weight per unit area on a narrow tire compared to a wider tire...

How about traction in the rain with the stock tires vs. an 8 inch wide tire?

Have to deal with a fair amount of rain & snow up here and have been debating whether there is really a significant difference in traction in wet weather between 7, 7.5, and 8 inch tires...or is it really just offset, weight, and looks I should worry about? (will use the stock rims for snow tires in winter...)...I will pick the tire with the most traction as I'm one of those drivers that naturally tends to use the gas pedal to make corrections, especially in the rex which is usually the best way to get the tail back in through corners...

Thanks,
rhk

 

Good points RHK. In the snow, the narrowest tire possible is best. The wider a tire in snow driving, the more the car tends to "float" on the snow where it's most advantageous to dig in and find a solid surface. Rain is similar, but flows easier and I'd put a wider tire with a "V" tread pattern up against a narrower tire with a standard tread pattern anyday in a hydroplane resistance test. However, a wider tire will have better traction on a damp surface.

 

Thanks!

So W-I-D-E-R is better (forgive the reference... ) in wet...

Although fun, don't want to slide around any more than I have to!...wouldn't want to drop that kind of money on new wheels only to find I had more control with the stockers...


New snow tires for the 6.5's this winter....New rims next spring (sunch a long wait though...)