RENNTECH36

OK...so I put some 19x8 and 19x9 Weds Bavaria II wheels on my 2005 E55. I put them on the car with 275's and 235's. They look awesome (pics to come soon) BUT...


there are a few problems:
1. The car feels CONSIDERABLY slower. I could barely pull on an 06 650CI BMW. Should an inch larger diameter and 10MM wider tires make this difference?

2. The ESP light goes off a lot more. If I am doing 80 in third gear M mode, and i push it to the floor, I know the tires arent slipping, but my ESP will kick on and cut power for a second. This happens at almost any speed, with any sort of intermediate-hard acceleration. What could cause this. I heard maybe my wheels are slipping inside my tires??? Any thoughts

3. The car seems to have a much different shifting pattern. It seems like it shifts to second a lot earlier than normal, and also sometimes it will start in second gear. My thoughts are it is because of the diameter of the wheels???/

PLEASE HELP before I take these beautiful graphite wheels off of my car!

Lancelot

It's a good bet the problem is caused by the one inch larger diameter. You are covering a greater distance with one revolution of the new wheel compared to the OE wheel so things are off. The ECU is measuring engine and axle rpm's (amoungst other things) and at a certain gear/speed/and engine rpm your axle rpm is too far off and it thinks your wheels must be slipping thus ESP kicks in. My bro-in-law was already warned for this happening at high speeds when he wanted to change tire size on his C250. I would consult your MB dealer/service station to be sure, and/or go back to a tire size that best approaches the original diameter...

(can't wait to see the pics of it all though!)

Kev04C320

As long as you keep the tire aspect ratio correct, the total diameter of the tire should not change. It looks like it's a cast wheel so going from 18 AMGs to 19s will add significant unsprung weight to your car, which is a big no no for acceleration.

Also, have you been driving in the city a lot lately? Try to reset the ECU settings (search the forum for instructions)

E55 RUSS

I dont think those probs are cause of 19's wheels and diff tyres...Is there any rubbiing ??? What profile is you tyres ???

jangy

You have a few things going on. Here is a little list of possibilities. I'd assume you have some combination:

The ESP kicking in without you feeling wheel spin is most likely due to the change in the diameter of the tires. The car calculates everything relatively as inverse percentages. Imagine when the car is turning and only think of the rear tires. By the time the car does a complete circle, the OUTSIDE wheel will have travelled a longer distance (and therefore more rotation) than the inside tire. Now, when you are spinning tires, the "delta" between the wheels gets exaggerated, since one wheel will spin more. By having a 2+ wheel and tire setup, you MAY be prone to more of these issues.

The larger diameter also kills your acceleration, since it changes your gear ratios. it will add top end, if you care.

The heavier wheels will DEFINITELY be noticed on launches. Not as much on short burst runs, but mostly on either long runs or just out of the hole. Unsprung weight is a KILLER.

Your tire aspect ratio and side walls may cause a difference in the lateral and vertical stiffness. If you are running a tighter lipped tire or one that has reinforced sidewalls, they will stiffen the ride. Often, that is good for handling since it helps to minimize the lag of getting the rubber tense. However, it kills the ability of the tire to conform and make better contact from the centrifugal force of acceleration. Drag cars run very low air and soft side walls for that vey reason. Try your car out with the tires at 40 psi and again at 20psi. You will notice that it is a better autocross car at 40psi and a better drag car at 20psi.

Sorry for the boring lecture, I didn't mean it that way.

Lancelot

That's what I tried to say earlier, also his speedo is off, indicating slightly less than actual, probably no margin anymore...

whoover

What tire sizes did you fit? To maintain outside diameter, you generally use one-size lower profile when you go up one wheel size. If you did, the electronics should be fine. If you didn't, they would be out of calibration.

You can confirm your fit accuracy here;

http://www.canadiandriver.com/tools/...c/tirecalc.htm

V12Godspeed

I bought some 20 inch HRE's 840, you mean to tell me that my car will be slower now? That sucks... I thought HRE's were supposed to be very light and great performance wheels, that is not good. Someone please say this is not so.

jangy

Larger wheel diameter = higher gearing (final)
That has nothing to do with HREs. 20s are not going to perform, they are going to bling. 18" HREs would have blown the factory ones away, because you could have had more rubber on the ground AND less unsprung weight.

SS3E55

Jody420 - its the FINAL (meaning wheel AND tire) diameter you must consider for issues of gear ratio and speedo accuracy. Consider the weight issue for acceleration.

So I have aggressive 20" wheels that have the very low profile to make them within 0.5% of stock diameter (and therefore circumference). Check the combination on any one of a number of wheel and tire size calculator sites (there's a Mazda one I like). However these wheels are heavier and I do notice that in acceleration. Also the ride is rougher too (less flex in the sidewall). They look great and I like that - always consider the tradeoff's and you'll get what you want.

Now there is a small upside (along with looks and finally being able to see those great brakes in their glory) is that the car definietly corners flatter and stiffer.