todinlaw

After I installed my Toe Links I went to the Alignment shop today with my OE 19 inch rims and a new set of R888's I told my guy that I also purchase a set of OZ 18 rims and will be running 18's for the season also. He told me that I better bring it back in with the 18's so we can see what changes are made from going from the 19 to the 18. He said it will change the alignment, mostly with the Camber.

He showed me a chart and it looks as if putting an 18 inch wheel on the 19 inch set up I will have less camber so when I go to 18 I will have to increase the camber a tic.

Does anyone have that experience and if it changed how much did it change. Did you find that you could not run both on the same camber set up??

Its always something.

tcsracing1

arenared

I cannot think of any reason why wheel size would have any effect on alignment. You are not changing the positions of the wheel hubs. Not even a change in unsprung weight would make a difference. Even a change in tire diameter, width, offset would not impact alignment. The only remotely relevant concern might be with a wholly different width or diameter that may affect clearances and therefore cause you to run a slightly different alignment, but that's a stretch. You may also want slightly different alignment to account for the different tires, but still the wheel change itself shouldn't change alignment where you need to "correct" it again. Am curious to see what the rationale is...

todinlaw

I think the change is specific to Camber. As I read your post I may not have articulated this exactly, but we did look at a chart that showed changes in camber relative to the size of the wheel 16,17,18 for example, but when you put your engineer hat on, it may not be the rim size but maybe the offset of the rim and was thinking if the tire size itself changes both in terms of rolling diameter and width. I am going from a 305/30/19 to 315/30/18 in rear for example, the 18 is a smaller rolling diameter tire.

I am not saying this makes sense that is why i am checking the real world experience, does this change anything. I can find out by going back and payslip another 250.00 to check it, but would rather not.

NJ-GT

Urgent. Find a new alignment shop.

Even with smaller diameter tires, as long as you keep the F/R diameter ratios, you won't have a change on corner weights, camber, caster, toe. No changes in the alignment.

However, running the car empty on gas or full, that will for sure change your alignment: camber and toe. So, your alignment shop may request you to re-align the car when your fuel tank is empty. Bring on those $250 checks.

If you're away of the stock F/R diameter ratios, you will have a slight alignment change, but not as significant as running an empty or full fuel tank. Moreover, if you are really far from the stock F/R diameter ratios, you'll be suffering from ABS errors and ice-mode brakes before you even notice an alignment change.

todinlaw

Maybe he was just looking for an extra 250.00. I am changing both Tire size and width going from 235/35/19 to the 240/40/18 and 305/19 to 315/18. so maybe the changes are so small nothing to worry about. Where do I send my check.

NJ-GT

The R888 you should use is the 255/35R18 on the 18" wheels (8.5" or 9"). The 245/40R18 is too tall, and you're already running a shorter rear 315/30R18. Toyo has a 305/35R18 that is as wide as their 315 and runs on the same diameter as the stock tires, this 305 can run with either the 245/40 or 255/35.

The ABS computer has a 5% tolerance compared to the stock diameter ratios. However, as you move away from the stock tolerance, you will notice a weird behavior on the ABS, it becomes more intrusive at the limits.

The stock diameters are f:25.5"/r:26.3". Running 245/315 R888 bring you to 3.8% out of the stock tolerance. Personally, I use 4% as the threshold for my autoX tires combinations, but for track tires I try to find sets close to the stock ratios.

va122

OMG Too funny. Rad's right of course.

todinlaw

The 18's are Nitto not Toyo so nitto do not make that change. I can tell you that others have told me that the 245/40/18 and the 315/30/18 combo will work. When I was looking for some ccw's last year John recommended that combo. so although I have not run them yet others have told me they have with not issues, I bought the tires already, so I hope they were right.