'99 SL tire size

another simple '99 SL question.
what was the stock wheel and tire size?
i am trying to pin down my speedo error. at the moment i have 18 inch Argus MG wheels with (i know they are a bad brand) 245/40 Nitto N555 ZR tires.
thank you for all the help

If you have an 18" wheel, 40mm profile will cause you to be .5mph off original in 20-40 1mph in 45 - 75 and 1.25mph in 80-150 (SLOW as in your speedo will say you are faster than you are)

At least that is the best I can remember from my research when I switched to 18s a year ago. I have a Stealth though, so even though our cars are basically the same there might be a little difference between my 95 and your 99.

thanks for the info. i have just been concerned about my speedo, i will be travelling down the highway, staying with traffic, and my speedo will say 85-90mph. it just seems odd sometime that on a highway marked for 65, everyone is doing 90. i know its possible but just very unlikely.

but thank you for the help

Not sure where you are located, but here in CA when you are lucky enough to get a freeway that isn't dead stop b2b traffic the only people going less than 75 are the old people... Even the stupid people do 75-80

not really my situation. i live just south of San Jose, i drive 101 to work and school. not bad traffic wise, but i don't remember ever seeing everyone doing 90.