NerdElectric

So when I bought my car less than a year ago the original owner had installed 245/40R18 size tires in the rear. I know that the car calls out 245/45R18 for the rear tires, but I didn't notice the difference until after I bought the car so I never got a change to ask the original owner why he changed the tire size.

I haven't seen any problems, other than the speedometer reads just barely faster than I'm actually going due to the tire size difference. So would any of you know why he would have gone with a smaller sidewall aspect ratio? Should this cause any problems? When I eventually buy new tires What size should I buy?

If it matters I have a 2008 Touring Edition, 6 speed manual.
Thanks

Spike100

245/40-18 is the ideal overall diameter for the front, but a little short for the rear. A 245/40-18 might cause problems with VDC. When you replace your rears, go with 245/45-18. --Spike

taryon

The 245/40 has a smaller circumference than the 225/45 in fronts and may cause VDC problems as Spike100 has said

NerdElectric

Thanks. Actually the reason that I finally asked about this was because I saw in another thread a guy was having problems with his VDC and tire size was called out as the most likely culprit. Thankfully I haven't had any problems with it (knock on wood), but if I do tire size is the first thing that I'll look into.

I also didn't know if there was some reason that he would have wanted a smaller sidewall in the rear or if that was something common that people do with these cars, so I thought I would ask.