Hello,

I just bought 17*8 rims (ET 35) with 235/45/17 tires which rub at the front. Will it be ok to put 215/45/17 tires on the front and stay with the 235/45's on the back? Will it affect the ASR with different tire size??

btw. my car is a '95 E420 which came stock with 215/55/16 which is the same height as 235/45/17 I believe.

This is the car with stock tires

http://www.cardomain.com/memberpage/535892

In order to do a true plus 1 fitment.......................add 10 subtract 10. Meaning 1 inch in rim diameter should add 10 to your first number 215->225 and subtract 10 from your second number
55->45. Try 225/45R17 all around. Also the 8" rim might be a lil too wide for the 215 tire.

I am not an expert, but I can think of two issues with different size wheels.

1. I had to buy snow tires in a hurry one time and I ended up with a wheel/tire combination that was just a bit smaller than OEM. As I remember, the snow tires were 205/55/15 instead of 195/65/15. The slightly smaller diameter confused my cruise control and it would not work. Even the dealer was surprised. They actually replaced the cruise module and when it still didn’t work they tried swapping wheels and tires from another vehicle and it worked fine. It turns out that even very small differences in wheel/tire diameter can mess with some of the electronics on our cars. I suppose if you carefully select tire width and profile, then you could get virtually identical diameter and not mess up anything.

2. With different size wheels and tires, you would also lose the ability to properly rotate the tires. Proper rotation can dramatically improve tire life, so it might be foolish to give up that opportunity.

As I said, I am not an expert, but I wouldn’t do it. I prefer matching front and rear.

__________________
I just couldn't give up on my 1995 E320.

I think it might be like always going back to that same bad relationship with an ex girlfriend.
You feel you love them too much, or you are just too stupid to know any better.



Flickr slideshow of my 1995 E320
http://www.flickr.com/photos/24145497@N06/sets/72157616572140057/

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

the shorter tire on the front will have a different sidewall deflection rate and will upset the handling .... not to mention the traction control system issues

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