I am thinking of ordering new wheels for my TTS. Current size is 8.5x19 and 11x19.
Considering 9x19 and 12x19.
Will the wider width cause any problems or advantages?
Thanks in advance.

 

Offset is as important as width so post those numbers too. The GT2 runs 8.5x19 and 12x19 so assuming offsets are OK, going to these widths on a TT shouldn't be a problem. I run the GT2 widths with OEM tire sizes and no problems. Don't know the advantages though.

 

Going to those sizes make sure that the car is 4 wheel aligned and keep the ratio of diameters from front to back the same as with the stock wheels (else you could potentially damage your diff).

 

Only if you change the tire width/profile...rim width doesn't create any "ratio" problems.

 

How does changes the dia damage the diff? What amount mm changes is considered bad?

 

I will be going with those new sizes too. 19x12 19x9.
Tire size should be 325/30 & 245/35 which will help keep it closest to stock ratio. I think if you went with 305 in the rears it will look a bit stretched.

 

+1 on what TT Chris said.

 

GT3 runs 305's on the 12 inch rim and they look fine.

 

+1 jh. Running stock size MPSC's on GT3RS wheels (just different offsets than the GT3's) and fit is fine. Different tires, despite same widths, may be stretched out a bit more on a 12.

Chris, do you have personal experience with these sizes? I'd like to +size with the next set of tires, but I'm just deathly afraid of frying the diff.

 

Maybe those GT3's are running cup tires which are a bit wider to begin with as opposed to Nitto's and PS2's of the same size
No I don't yet. But I will come next track season. Will let you know how that pans out.