Since Im getting a small brake kit, I have the option of putting going either 15" or 17" wheel size. This is purely for AutoX / Track days with no street use.

Any advantages / disadvantage going either way ?

 

Why are you buying a smaller brake kit for a car that is being built for autox and track?

As for your questions, 17s. Larger wheel/tire selection in consideration for wheel width, tire with, and compounds. No one who drive an Evo for autox runs anything smaller than stock!!!NO ONE! Common size is 17x9.5 wheels for STU, and 18x9.5 for BSP and SM. Anything smaller will not be beneficial.

 

its primarily a RallyX car... autoX duty is secondary hence the brake downgrade. Would it be possible that no one runs smaller than 17's because they wanna retain the big brakes ? I can find a set of RA1's in 15 and Ill be good for a long time. Im guessing car will accelerate way faster with the 15's due to shorter tires....etc ..

 

Well, you can run whatever you have. Question is, how competitive do you want to be? You have mentioned autox and track, not rallyx. Rallyx requires a completely different tire setup as functionality is different.

 

just thinking outside the box here but, keep ur stock breaks, get 17''s for autox and switch ur breaks every time u transition from rallyx to autox....

 

So why don't you just get smaller tires??? 40s,35s... Toyo r1r's are made in 35's. But I don't see the benefit here...

 

too much work swapping brakes... the small brake kit can support both 15 and 17 tires.

 

I already have multiple sets of gravel rally spec and studded ice/snow tires for rallyX and Winter rallyX. I am aware of the functionality difference between different tire setups. What I dont know is if 15's will be as good as 17's, what are the pros and cons of either setup. I will be running Ra1's, R888's or NT01's

 

For any of those tires, 15's aren't going to be wide or tall enough. The gearing will be bad for autox (lots of 2-3-2 shifting), and you'll overheat the tires quickly. The only 15" tire worth running would be the 275/35-15 Hoosier A6, and that still has the gearing problem if the car isn't built around it. Look for the widest tire you can fit that will have a diameter around 25" or so. If you have different gearing than stock or are working within certain rules that might change things.

 

thank you sir !! this is the info I was looking for. I will stick to 17's