225/45/15 vs 255/40/17 RS for autox

[bigo]

With bigger rim size and wider tire you'll get a bigger contact path so the car should be quicker on the corners but will suffer on the long straights and the fuel economy will be worse. The big wheels also kill torque of the engine on wheels. If your riding a is i wouldnt go higher than 16 in sport. I would go with the bigger rim only to fit bigger brakes.

[BlackbirdM3]

Unsprung weight. Good luck getting a light set of wheels in a 17, and by light weight, Im talking less than 15lbs.They are out there, but be ready to drop a lot of cash for them.

I don't know that 17s are the answer. I'm sticking with 15s, I'd run 14s for autoX if I could find a set of 5x120s in an 8 inch width assuming they would clear the brakes, and I don't think they will.

Will

[spencers]

It's all about getting more rubber on the pavement.

Make it fit!

[CrazyB]

Great nice to hear someone who actually went in this direction.
And i do love my 225 rs3 on 15x8 best bang for the buck autox tire.

[kilgojr]

My brother and I both autocross ALOT. We have run all sorts of tire combos. 15x7 with 205s with 225s, 16x8 with 225s and 245s, and 17x9 with 255. I will tell you that a 255x45x17 is WAY better then any of the other tires that we ran.

Now, we have also run 255's on a 17x8.25 front and 17x9.75 rear and it was still better then the previous 17x9 with 255 setup. This is all experience with a Kumho XS. My brother will be running a 255 Hankook RS3 this year in the 255 with 8.25 and 9.75 wheel and we only expect it to get even better because of the tire experience. The RS3's are definitely a better tire then the XS was.

As far as the gearing, we were running a 4.10 diff on the M20 with boltons. And we still had to shift into third quite a bit on the faster National Tour and Regional courses. We saw no loss of acceleration with the tires, the car was just as fast as with the smaller 23 inch tall 15 inch tires. And we carry way more speed through the turns, so all in all your times will improve.

As far as fitment, your gonna have to roll the fenders, or just pony up and get the rivet on flares. The latter is what we both did.

[CrazyB]

I currently have a 3.73 in the car, but I have a 4.10 seating in the garage also so that should change the gearing if that becomes an issue. As far as clearance I am fine with cutting the fenders and removing the liner, the car is not a daily driver.

I was more going to see if anyone ran this size and how the car feels on the larger tire.

[2002maniac]

My only worry would be the gearing disadvantage. 255/40/17 is a lot taller than 225/45/15.

[BlackbirdM3]

Do you have all the fender well plastic stuff removed? If not, tires will rub like crazy. Also, a bigger wheel is heavier, and will mess with your gearing as well. I thought my M3 drove better with a 225/45/15 than it did with 215/40/17s. Everything was better, the turn in was more crisp, braking was better, acceleration was better.

My vote, stay with 15s, I see no real gains being made with 17s.

Will

[CrazyB]

I am currently running a 225 RS3 on a 15lb 15x8 wheels
For this season i was thinking of moving up to Rota Grids in 17x9 and run the 255/40/17 RS3
Anyone have experience with running the 255 tire and have any feedback.
One of the reasons i am making the jump is for next season i can run 275/49.17 r comps on this wheels also.

I know the fenders might not clear them but i am willing to add rivet on flares or custom flares to clear the rubber.

Just curious if anyone made the jump form 225 15 to a wider 17 inch tire and how the car felt.