Tire Size Again.

I have general tires. They are p275/40ZR17. I have a stealth RT TT. Ive been looking in my owners manual and service manual and they say that the Stock height Is 45 not 40. Now my speedometer reads 15mph lower than im accualy going. Could this be the problem? Also I thought my struts were shop becasue im getting bad vibration over bump. Could this be the culprit? Thanks for the help!

Are you getting a bouncy noise/reaction when you go over bumps. If you push down on the corner of the car, does it go up and down multiple times? If it bounces more than once or 2x, the strut should probably be replaced.

I don't think those sized tires would throw off your speedo that much...that seems a bit excessive. But as said in the other thread, those tires have been used by others before.

By the way, how do you know how much your speedo is off, unless you got drive by one of those visual radar things.

275/40 and 245/45 are less than a millimeter difference in sidewall height.