Recommended stock tire size for 1984 500SEL is 205/70 HR14. But my car now has 15" rims. So what tire size for 15" rims should I use to keep the speedometer accurate?

According to Tire Rack's site, looks like 205/65 would be size for the 15" rim. I didn't look at diameters of tires. That would come out to about a 25.5" diameter. 205/70 on a 14"rim should be about 25.4", so it's about as close as you can get.

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Earl McLain
'02 C230 Kompressor
'89 560 SEL "Frau BlueCar" (retired April 2004)

205/65 in a 15" wheel would yield the same circumference, thus keeping your speedometer reading correctly.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".