I was wondering for my next set of tires, I'm planning on upsizing the width one size. Anybody know if this is gonna affect any of the sophisticated systems in the car? Such as VSA for example? This is probably the most high-tech car ive ever owned, I'm just worried about messing with the computer/electronics. Any input appreciated.

 

no at all.. I have 235/40/18... on 18x7.5 +45!

 

if you do the same with all 4 tires, no problem. If there is a difference in tire diameter between the 4, that's when VSA freaks out (that's why when you use the spare, VSA should be OFF).

 

if you go to a 225/45/17 tire, your speedometer will be off from TRUE accuracy by close to 7% (there was a thread recently where this was detailed, the STOCK tires are already in error by about 2-3% and it gets worse when you decrease the circumference further with a 225/45/17) essentially, your speedometer will read fast, and your odometer will gauge mileage to fast (over the course of 50,000 TRUE miles with 225/45/17 tires, your odometer will register anywhere from 1000-4500 EXTRA miles depending on tires and how quickly they wear down.


if you go with 225/50 you will have the opposite effect on your car, your speedometer and odometer will be in error but on the opposite end, your speedometer will read slow and you well effectively SLOW DOWN your odometer


if you get 235/45/17 you will be within 1-2% of stock size, which is still 1-3% off as it is, so you will still be in error, but not as badly as the other 2 choices

 

I wasn't talking about changing the profile, I was just talking about upping the tire width from 225, to 235's all around.

 

when changing a tires width, typically, you MUST change the profile for the tire to remain the same (or close to the same) size as the stock tire....a 235/50/17 will be SIGNIFICANTLY taller in profile than a 215/50/17 so it wouldnt fit....


your tire options for stock rims are as follows:


stock size = 215/50/17

225/45/17 (7% + error)
225/50/17 (3-5% error)

235/45/17 (1-2% error)


other size tires will not fit on stock rims. also, if you go with a tire thats significantly wider, you will slow your car down because there is more work required from your car to turn those bigger tires. if you go too small, you will heavily throw off your odometer and speedo.

the only way NOT to mess up your odometer and speedometer is to stick with the STOCK SIZE tires.