Question about using the same size rims front/rear?

[Sinisfun]

Why do the rear wheels need to be larger overall diameter than the front tires? I've found a set of cheap 16" Volks (I haven't checked if they are real yet) that I could use for the track instead of my heavy HP's. I don't mind swapping the rubber, but I was wondering why the rears need to be larger.

 

[Oyagi]

The ECU will trip out and throw the traction control at you if you run identical diameter wheels front and back. It is set to expect a larger diameter wheel in the rear. If they rotate at the same rate it thinks its slipping. I used to have a set of jdm BBS Stern rims 17x7.5 fronts, 17x9.5 rears. I had to make sure the rear tires had a taller sidewall otherwise I had to switch the TRAC off everytime I stated the car. It was a pita.

 

[Red]

The ECU will trip out and throw the traction control at you if you run identical diameter wheels front and back. It is set to expect a larger diameter wheel in the rear. If they rotate at the same rate it thinks its slipping. I used to have a set of jdm BBS Stern rims 17x7.5 fronts, 17x9.5 rears. I had to make sure the rear tires had a taller sidewall otherwise I had to switch the TRAC off everytime I stated the car. It was a pita.

I wonder what the 02+ solution is - since they're 17 front and rear (I forget tire profiles - I've been away too long) but I'd assume its easy to calculate, otherwise, yes, you'd need either the Traction Control program of a newer car (assuming its different) or a higher aspect tire on the rear - which you could do easily, some performance hit to higher sidewalls, if you're looking at this for the track I'm not sure it makes sense?

 

[angus]

as long as you stick close to the stock overall diameter (not the rim diam. ) you should be ok , just make sure your track tires are available in the size you need , also make sure the wheels are the right width / offset

 

[BioBanker]

Yes, make sure you have the proper total diameter so that youre not making TCS an issue (I think rear has to be 105% of front), but also dont play with your gear ratios too much or your speedo and shift points and acceleration will be off. ALSO, dont forget that you need a stagger width too, so if all the rims are also the same width, that may also be an issue.

Visually, smaller rims in the front look much better if your car is lowered. I had 18 volks from my S2000 that fit fine, they didnt look right so I sold them for a 17/18 set up.

 

[RP-Motorsports]

The reason behind the fronts being taller than the rears is for looks. We run 17/17 at the track all of the time to save weight and cost of tires.

The front fender on the NSX is like a Honda Civics, and can only fit a small wheel. The rear fender is larger, thus it takes a larger wheel for the proportions to look right. A 17/17 16/16 18/18 etc makes the rear wheel look small.

It all comes down to the tire size, not the rim size for TCS issues.

I can pretty much stuff any wheel combo onto a customers car with the use of a calculator and my tire book. We have went as large as 11.25" wide with a 335 tire in the stock rear! We also run 235 track tires up front all the time as well. I have seen 19/20 combos etc.

The best bang for the buck is a 17x7.5 to 17x8.0/18x9.0 to 18x10 combo with offsets between +35 and +40 with a 215-40-17 front tire and a 265-35-18 rear.

The next popular size is 18x8.0/19x9.0 to 19x10 combo +35 to +40 area with a 215-35-18 and a 265-30-19.

Some people use a 275 wide rear.

For the track we run a 17x8.0 + 43mm with a 235-40-17 and a 17x9 +40 with 275-40-17 Sometimes we run a 18x9 rear with a 275-35-18.

I can always help figure out custom sizes/offsets for wheels and/or tires. Just PM or email me.

Tom

 

[Sinisfun]

Thanks a lot Tom, that's great. Now if you can just help me afford the rims, haha.