I'm going to get some 15" OEM wheels from a 87 560 and put them on my 81 300sd that currently has the factory 14" wheels. What size tires will i need to keep the speedometer accurate?

doing what the factory did when they switched to 15": put on 205/65 size. If you have been running 205/70 X 14, the speedo should be almost exactly the same, but if you have been running 195/70 X 14, you're going to get a bit lower speedo reading at the same actual speed -- probably just enough to compensate for the typical factory error. You will lose a few percent in load capacity, but that didn't seem to bother M-B -- they just recommended a few more pounds pressure. Personally, I would go with 215/60 (speedo would read higher at same actual speed) or 225/60 (if you can find them) for the modern wide tire look, but many will disagree with me.

Actually, I think the previous post got it just backward on the speedo registering bit...larger diameter tires result in a slower reading on the speedo than the actual road speed. If you have been running 195/70 tires instead of the 205s, then the speedo has been reading faster than actual. If you put on a tire with a larger than original stock diameter, the speedo will register slower than actual, I'm repeating myself here, am I not? Anyway, it's an easy mistake to make, and one you may not notice until that cop pulls you over.

I checked Tire Rack for the +1 size for my 107 SL and the equivalent size (O.D.) is 205/65X 15, like was mentioned by Fimun Fit.

Cheers,

230/8

What I meant was that if you have been running 195/70 14 and switch to 205/65 15, your speedo readings will _now_ be slower for the same road speed than they had been with the 195/70 14

I currently run 215-70-14's on the SD. I've found a set of 15" factory wheels for it and will switch to 215-65-15. I'm not all that concerned with the speedometer error. It's about 3 mph as compared to the stock 195/70/14's.

The SDL was recently fitted with the same 215-65-15's and the clearance to the tie rod is less than 1/2". You probably could get away with 225-65-15's if you want, but, the tire might be getting a bit close to the tie rod end.