Eiskalt

I am getting ready to put 20" wheels on my 2005 SL600. The tire shop is recommending 285/30 size for the rear tires to better protect the wheel and keep the ride comfort acceptable. My initial plan was to put 305/25 on the rear tires. The 305/25 tires have a total diameter of 26", which is identical to the OEM set up. The 285/30 on the other hand have a total diameter of 26.8". The rule of thumb that I have followed so far is to stay as close as possible to the original diameter, but I like to hear if someone has tried the 285/30 tire size and if it has caused any problems. By the way, the wheels have a 25mm offset and I am being assured that the wheel will fit perfectly, since it is especially made for MB.

Havoc

I have 285/30 in the rear with no issues whatsoever. Your tire shop is correct in recommending 285/30 size for the rear tires to better protect the 20" wheels and keep the ride comfort acceptable. When I had 295/25 my wheels bent twice and the ride quality suffered.

Eiskalt

That is great to know. I appreciate the feedback. I like the wheels that you have on your SL 55. Are those HREs?

Havoc

Thanks bro!

Yes, they are HRE 597R wheels
-8.5 x 20 front
-10.5 x 20 rear

Michelin PS2 tires
-245/35/20 front
-285/30/20 rear

NEMES1S

I suggest a set of pilot sports, love mine 255 35 19 on front and 305 25 20 on back

Rick SL55

305 25 20 on back, wheel will look 100% better!.

Eiskalt

I don't think I will be able to put 305/25/20 on my wheels any time soon, because they are only 10 wide. Below are a few pics - obviously not my car and I was too lazy to remove the advertising.