Car shifting funny after new wheels

[mastatikle]

Originally Posted by brad850csi

275*.35 = 96.25mm
285*.35 = 99.75mm

325*.30 = 97.50mm

285/30/21 as previously mentioned. Stock dimensions have a .5" gap

[mastatikle]

Originally Posted by Derboy

That’s what I mean. If the computer is monitoring inputs from the ABS system which may also take into account data from the rear differential and given that the DCT system is computer controlled it’s stands to reason that given everything worked fine before, that your problem is due to you upsetting the balance of the car by changing the rolling radius between the two axles.

I’m not technically proficient enough to understand how or why but logic points to the wheel change being the problem. Interested to know what happens when you change them back.

Yeah I'll switch them back in the a few hours. Have been busy. Really curious as to what's the issue. I was waiting to do the switch until new low dust brake pads came in but they just arrived. Hopefully everything goes back to normal.

[M6-Coupe]

Originally Posted by mastatikle

Handling from the performance aspect I have not been able to really test because it's been ~60 degrees average where I'm at. But straight line, the car gets much more traction. I used to spin to 60 (top of 2nd gear) with 285/30/20 pilot supersports. Now I can grab traction in first!!! That's without an alignment and this cooler weather. Ride is SIGNIFICANTLY better. It was the first thing I noticed. Rides much much smoother, even with the smaller front tire. Turn in is a little better, but can't really prove that. I'm going up to 285 in front so not sure how turn in will be. Stopping should be improved though.

Well ypu get better traction because the The Force on real wheels are reduced about 6%.... it's the same effect of reducing torque by 6% on stock car so basically you get better traction but on straight line such as 0-100 mph or 1/4 mile your car is now slower than what she was with OEM wheel. Ride is smoother because you have increased the center of gravity... It is like comparing a 2 seat car with SUV. SUV has smoother ride because cannot feel all of the unevenness of roads. For sure handling is much worse sepecially if you want to push the car to the limits on cornering or tracks because of increasing the center of gravity.... you should post some pics

[mastatikle]

I put it back to stock today and everything is back to normal with the shifting so different diameters of custom wheels are definitely throwing something off. Changed them back to stock was a MAJOR PITA to put it lightly. One side went smooth and then one wheel lock snapped 2 keys and stripped one. And when the key snapped I chipped a wheel with the ratchet so that ruined my day. Spent hours driving around trying to find a key/solution to get the wheel off. They were perfect now there's a chip that's going to bug me forever. DO NOT USE SPLINE LUG NUTS! Going to keep car on stock wheels until I feel like ponying up another $1100 for two more new front tires and $800 to get wheel refinished 😡. Oh and still have to get new lugs and install the "low dust" brake pads. Car looks like crap now without the wheels lmao. Only have two weeks left of nice weather so hopefully I can make it. I'll try to add photos now

[mastatikle]

Originally Posted by M6-Coupe

Well ypu get better traction because the The Force on real wheels are reduced about 6%.... it's the same effect of reducing torque by 6% on stock car so basically you get better traction but on straight line such as 0-100 mph or 1/4 mile your car is now slower than what she was with OEM wheel. Ride is smoother because you have increased the center of gravity... It is like comparing a 2 seat car with SUV. SUV has smoother ride because cannot feel all of the unevenness of roads. For sure handling is much worse sepecially if you want to push the car to the limits on cornering or tracks because of increasing the center of gravity.... you should post some pics

Ahh I see, I kind of miss the wheel spin tbh. The ride comfort is worth trading for the lesser performance. I rarely push my car in the turns and now rarely push it at all with these wheels on it haha. I'll try compressing photos to upload now.