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Discussion Starter #1
I never really considered doing that but I found a great deal and bought the OEM 20 inch rims for the R class. My question is whether or not it is "plug and play" Do i need any adjustments to speedometer etc., I currently have the 18 inch tires. The new tires will be 265/45/20 vs 255/55/18
 

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check if there are 5x112 for R...if they are direct MB then no need for offsets..just install and get good H rated or better tires...please post pics
 

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2006 R350 1999 ML430 2003 Audi Allroad
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You DO need to know what the rim offset is on the

new set. Offset is the distance from the edge of the rim to where the center bolts to the hub. If the offset is wrong, the rims will either tuck into the wheelwell too far, or stick out too far. Stock rim offset on the Rclass is around 60mm.

The tire size you quoted is spot on for this conversion, however.
 

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08 R350, 07 Acura RL, 1989 Honda Shadow VLX600 (10K miles)
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new set. Offset is the distance from the edge of the rim to where the center bolts to the hub. If the offset is wrong, the rims will either tuck into the wheelwell too far, or stick out too far. Stock rim offset on the Rclass is around 60mm.

The tire size you quoted is spot on for this conversion, however.
He(mitaka) got 20" OEM rims for R class (R63). so there is no problem with the offset.

mitaka,

You got the same rim as me. You do not need any speedometer adjustment.
The outside dia. is very close to both tire sizez, the wall rubber on 20" is lower than 18" tire. (265 45 20 tires is equipped on R63).
If you replace with 275 45 20, then your speedometer will only off around 2-3 MPH.
 

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+1 on what Asian said. The speedometer reading will be 1.2% slower than what it will read with your current wheel/tire combo. Actually this translates to 1.2 mph off when doing 100mph! so for 65 mph it is less than 1 mph off which is negligible.

Check out the calculator, it is very handy!
Tire size calculator

+1 on posting pics of your ride with 20 inchers. I am not into bigger rims than 18 or 19 for comfort reasons but I admit bigger wheels usually look nice up to a point. Like everything else in life, larger than 20-21 inches the rims look very ugly IMHO , the ricer type! 20 in should be cool!
 

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Discussion Starter #7
Thanks guys for the input. Very helpful.
 
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