How To Take Advantage of Bigger Diameter Wheels

I am moving up from 15 to 17 inch wheels. Is there anything special I can do to take advantage of this for my trackday car?

put in bigger brakes that actually require a 17" wheel to clear them..

Probably not going to happen. Not a lot of big brake kits available for Nubiras. I'm moving up for tire selection, not because I really want to, btw.

novaderrik wrote: put in bigger brakes that actually require a 17" wheel to clear them..

even that's iffy. I was just reading AngryCorvair's June 2008 article on brakes, and it said:

Big front calipers also require more fluid volume, which means longer pedal travel and less fluid reserve for when pad fade strikes. So, unless your system is rear biased, big front calipers are going to hurt, not help, your system balance. And if your master cylinder was marginally sized before the swap, you could wind up putting all your pedal force into the floorboard rather than into generating higher line pressures.

Angry listed two reasons why you might actually need bigger brakes:
1) if you need less unsprung weight (big ones are often made of aluminum, which could be lighter than the brakes you have)
2) if you need bigger pistons for more clamping force

Bigger brakes carry a long list of disadvantages in exchange for higher heat capacity and more clamping force (which you don't need if you can lock up your wheels on demand). Increased unsprung weight is on this list unless you change rotor & caliper materials ($$$$).

The only other things I can think of is that bigger rims can make room for a brake vent system and some suspension mods like roll center spacers and flipped tie rods.

No chance I'll get better cooling as a side effect? My 15s are pretty tight over the calipers.

Any chance I can use the bigger wheels as fans to evacuate the high pressure zones under the car?

My suspension geometry is pretty good right now. If I went with RCAs I'd have a serious jacking problem on my hands.

You won't get any cooling improvement just from the larger wheel size. You could get wheels with shaped spokes that act like a fan to suck air out from under the car and cool the brakes, but a brake vent system would probably be more efficient if you only want brake cooling (since it has a similar power draw to running 4 big radiator fans).

You have more room for roll center and bump steer correction at the knuckle end to compensate for lowering the car.

Brake ducting to the backing plate will fit more easily.

You can keep the same calipers but use a larger diameter rotor with an aluminum hat to bring unsprung weight down (or, keep it as a lateral anyway). That way you get more heat sink and torque but do not change fluid volumes. If you had adequate brake before and you aren't increasing speeds though... then it's just wasting your time and money.

The lower profile tires (keeping the same aspect ratio, I assume) with stiffer sidewalls will help "crispness" all on it's own.

Can't you get wider 15"s? I'll bet you that the 17" tire and wheel combination will be appreciably heavier, and the increase in rotating mass will off set any traction gains (assuming for similar rubber between the tire sizes).

Lower aspect ratio tires of course.

I would assume the tire selection in Korea is a bit more limited than in North America.

Appleseed wrote: I would assume the tire selection in Korea is a bit more limited than in North America.

why? a lot of the tires we use here are made there.

For street tires, I'm pretty much not getting anything bigger than a 205/50/15 unless I want rock hard and off brand.

I need to stay with street tires for the class I want to run.

I guess I could really slam the car and then make RCAs. That would be good. Hmm.

BTW, here are the donk wheels in question. Pulled the trigger today and got the set, including tires, for $250.