You are asking the right question, because your E420 has ASR traction control which compares the wheels speed/rotation among *ALL* four wheels.

Our 1993 500E's (W124) everyday stock tires are BFG KDWS 245/50R16 which has an outside diameter of 25.7-inches.

When I go to the track, I run 225/50R16 Nitto 555R drag radials (on the rear's only), which have an outside diameter of 24.9-inches. That's a difference of 0.8-inches.

If I don't *turn-off/disable* ASR traction control and accellerate hard, or go over 65-mph, the difference in rotational speed causes ASR to turn on and go into FAULT mode which means only 40% power is left, until I restart the car.

In short, the 0.8-inch difference causes the ASR to go into LIMP home fault.

Per TireRack's numbers for a Kumho 712's a 235/45R17 tire has an outside diameter of 25.3-inches and 215/45R17 tires have an outside diameter of 24.6-inches. The difference is 0.7-inches so I would venture into saying ASR will be triggered, especially if you accellerate quickly or do some quick turns.

I would order the AMG spacer kit (do a search on this board) and roll the front fender lips so you can run 235/45R17 tires up front.

If you still can't get 235's to work with the spacer-kit and rolled-lips, then purchase 225/45R17 tires up front which have an outside diameter of 24.9-inches; thus the difference between the two would only be 0.4-inches, and would be very slim to trip the ASR.

Moreover, 215/45R17 are usually load-rated at 87 (1201-lbs). thus, they usually don't have a high-enough load factor.

All W124's except the 500E expect a load rating of at least 91 (1356-lbs for the stock 195/65VR15).

Your 235/45R17 tire most likely has a load factor of 94 (1477-lbs).
215/55R16 tires most likely have a load factor of 93 (1433-lbs).

Going to a tire with a lower rating than 91 (1356-lbs) will lead to premature tire wear and/or failure, esp. of the sidewall.

:-) neil
1988 E36T AMG
1993 500E