I found some bundt-cake style spares (never on the ground) at a local salvage and picked up 4 of them. Had new tires mounted on them for my SL about a year ago and put the rims from the SL on my SD because they had newer tires and were in better shape. With me so far? New tires/rim on the SL; old but better rims/tires from SL on the SD. Finally got around to refinishing the spare set last week and took the Tootsie Roll (SD) in to have the tires remounted/balance/rotated. Went back to pick the car up later and the guy asked me if I knew the refinished rims were narrower than the ones he took off. NO, I didn't. I guess the SL came with wider bundts than the SD? The refinished rims were the originals from the SD and he had no problem putting 205/70/R14s on them. He's a pretty good local guy and didn't think I would have any problem, but thought I'd run it by the experts. Should I be worried about this size tire on a narrower rim? I might refinish the wider rims later, but my fingers and still blistered and sore from the last round...:p

Thanks!
TC

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TClanton
1980 450SL 90K
1980 300SD 112K

a V8 engined SL would come with 6 1/2" wide rims, and a 300SD with 6", although a 450SEL is likely to also have 6 1/2". What I'm not sure of is which year the 6 1/2" rims switched from c.29mm offset (unmarked) to 25mm. Obviously, the car with the 1/2" narrower rims will suffer a small handling disadvantage, all other things equal, but just don't try putting 6 1/2" ET29 rims on a W123 car, because you are likely (but not absolutely certain) to have problems with the tire sidewall of anything wider than a 205 rubbing lightly on the rubber boot of the tie rod end during some suspension movements. I'm not aware of any clearance problems with your two models.

As long as you have no clearance issues, they will be fine.

The most important thing for you to check since they came from different cars is to ENSURE that they ALL have the same offset. This is the ET number that is cast into the inside of the wheel.

If the offsets don't match, get wheels on there that DO have matching offsets. This would really do some crazy things to the alignment of the car.

Good luck,

There shouldn't be any problem with a 205/70/14 on a 6" rim as long as the wheel offset is the same (or very close) as Larry said.

A given tire size will fit a range of wheel rim widths but the narrower the rim, the more the tire sidewalls get squeezed. This results in the tread cross-section of the tire being made more round which in turn puts less useable tread in contact with the road. The narrower rim also allows more tire 'roll' during hard cornering which also affects its grip and will cause it to run hotter.

A wider rim allows the tire to sit flatter on the road giving a larger contact area = more grip & better handling. Even with the same tire size the wider rims within its fitment range will give an advantage in performance.

Andy