msdbsptc

So since the Potenzas suck i want better tires. I may be able to trade my tires to my boy who is gettin rid of his car. Ill get his tires for free. Only thing is theyre 215/40 17 tC i believe is 215/45. So will it work or will my speedometer be out of whack or something.

KeyLaTaN

i think they should work...i have 215/40's as well but sittin on 18"

The_Instigator

It will fit fine. The /40 means aspect ratio of the sidewall or percentage of the tread width the tire height is. In other words with a 215/45 your sidewall is 96.75mm or 3.8"and with a 215/40 your sidewall will be 86mm or 3.4".

Should not have a dramatic effect on your speedo if any at all. Not all tire manufacturers measure the same anyways so its not always exact.

tcengel

Remember that it will also affect your gearing a bit. You will be cruising at a slightly higher RPM on the highway. This may not be a big deal, except the TC gearing

Munch

Yeah it's alittle smaller overall diameter, but it will work. The speedometer will definatley be off. I'm running a 225-45-17 Nitto winter tire on mine, with a 17x8 inch wheel for the winter.

msdbsptc

I went to one of those online tire calculators and it said there would be a 3.4 percent change in diameter. it also said that staying safe means staying within 3 percent and that goin anymore percent can cause brake failure. Is it really that serious or should I do it. Remeber there is no goin back cause once we trade, his car with my tires is gone.