Tire sizes will it hurt

[Edubbz60]

Im thinking about putting a 245/45/18 on my 2003 M45 the stock size is 235/45/18. will there be any problems withe this tire change. And what is the differnce between the two? I keep getting different answers from every tire co. Help im going too buy within the next day or two.

[szh]

Im thinking about putting a 245/45/18 on my 2003 M45 the stock size is 235/45/18. will there be any problems withe this tire change. And what is the differnce between the two? I keep getting different answers from every tire co. Help im going too buy within the next day or two.

IMHO, the 245/45-18 is an excellent size for the stock wheels. Since you have a much better selection available in that size. Please look at the Basic Specs sticky in this forum ... I have a detailed list of possible tires listed in that size.

My personal recommendation would be the Goodyear Eagle F1 GS-D3 in a 245/45-18 size, with a good load index of 100. An excellent summer tire. Do NOT use it in freezing weather or snow!

Z

[busaboy]

Another option is 245/40/18. Just put Continental ContiProContact XL on my car and was amazed to se the MPH versus RPM stay almost the same and the tires handle a lot better than stock.

[szh]

Another option is 245/40/18. Just put Continental ContiProContact XL on my car and was amazed to se the MPH versus RPM stay almost the same and the tires handle a lot better than stock.

The typical error for most 245/40-18 tires about 2.8% from the stock 235/45-18 size. This is from tire/rotation per mile numbers in my spreadsheet - not a simple calculation from the tire diameters (which are prone to some error, since they don't take tire loading into account).

255/40 and 245/45-18 are closer - around 0.5 to 1.0% error in the speedo, but 255/40-18 needs a 8.5" width wheel (the stock wheel is 7.5"). Hence my recommendation for 245/45-18.

Z