Cintoman

Hey Everyone,

I just recently swapped my winter tire/wheel setup with my summer ones.

For my summer rims, I bought some new AMG-replica C55 twin double spoke wheels from a company in California called Eurotech Luxury Wheels. They look great, but the fronts are 1/2 inch wider than the OEM wheels that came with my car (2005 C230 Kompressor Sport Sedan - the funnel style rims).

So now, fronts are 8.0" wide versus OEM's 7.5" wide.

I had my OEM Michelin Pilot Primacy tires mounted on these new 1/2" wider wheels. These tires are 225/45 R17.

As a result of this, when taking the car out on the highway tonight, and basically doing some panic lane-changing swerves, the front end felt like I was driving a bus. Turn-in is horrible, and no longer razor sharp like before. Feels like the tire is rolling underneath itself.

My questions are: Would a 1/2" larger width wheel make THIS MUCH of a difference? I know the tire looks a bit different mounted, whereas now, the tire edge is at the same vertical plane as the edge of the wheel, where previously (and like my rear tire is now) the tire would bulge a bit further out from the wheel.

Tire pressure is at 36 psi.

I'm also noticing a very low speed thumping coming from the front. Tires were fine when removing them in the Fall, and the wheels are brand new, so they shouldn't be bent. At high speeds (<30mph up to 100mph), I don't notice any thumping or vibration in the steering wheel. Could this skinnier tire on a 1/2 inch wider wheel be wobbling side-to-side in the wheel?

In reading specs for wheels somewhere (tirerack maybe), I believe they say an 8" wide wheel can accomodate tire widths from 215 to 235's. So I wouldn't have thought this would be a problem. BTW, the exact wheels I purchased are on eBay.

Linky: http://cgi.ebay.com/ebaymotors/17-me...5112QQtcZphoto

Do you suggest I change the tires out from 225/45 to something like 235/40? Will this affect the speedometer and wreck even more havoc on my front end (suspension-wise, toe, camber, etc)? How's the height difference between the above 2 sizes?

Any suggestions? I almost feel like putting my winter tires back on, as they had far better turn-in than these do now.

Thanks a bunch.

Paul
(Cintoman)

Luke@tirerack

you have two completely different issues going on so, let's talk about them 1 at a time ...

#1.) sloppy handling ... You mentioned the reduced turn in and or steering response. My first thought would be tire pressure but 36 psi wouldn't yield a bad turn in so rethinking things I would say lower the rear pressure which would lead to better rotation

#2.) thump thump ... flat spots are the typical cause so, the obvious question would be how were the tires stored? are the wheels hub centric? what is the lateral runout & radial runout?

Cintoman

Hi Luke,
Thanks for you response. To answer your questions...

Yes, both front and rears are at 36psi, but I'll drop the rears down a bit. Do you suggest any particular pressure or should I just go by the placard?

I don't know if reducing the tire pressure in the back will help much because it still feels "front-end" related. Even when driving say 35-40mph, and I gently jerk the steering wheel left and right a bit, the front end feels floaty and sloppy.

When I did the tire/wheel changeover, I also had my alignment done. Because these are new wheels, and their offsets are different than the OEM ones, would the alignment guys need this info to properly align my car? Would they just plug in the specs for an OEM tire/wheel setup?

Another thing I was thinking was regarding the front tires. I have the OEM Michelin Pilot Primacy summer tires. I believe they're directional, but couldn't find any "<---rotation" or "mount this side out" engraving on the sidewall. Could it be that they mounted the tires incorrectly (backwards for lack of a better term)? I've looked at the thread pattern, but it gets a little weird trying to decipher which way the grooves should go correctly.

As for the flat spots, well, I had the tires stored in my garage loft over the winter (always >30 degrees in garage). I know at least 3 of them were laying flat, stacked on top of each other, but I can't for the life of me remember if that 4th tire was stacked on its side or upright. All of the tires were unmounted. Would they still develop flat spots unmounted and pressure-less?

Wheels are hubcentric. The wheels are brand new, rear tires are brand new, and fronts have about 80% thread remaining. I did notice some scalloping on the fronts when I removed them in the Fall. This scalloping was causing a faint buzzing sound when driving at highway speeds, but no thumping. As for lateral and radial runout, I'm not sure. Isn't this the wobble left to right of the tire on the wheel? Would a DIY'er be able to determine this, or would a tire shop have to?

Would a change from 225/45R17's to 235/40R17's in the front help the cause?

One final note...the lugs the CA company sent with my wheels are a bit too short compared to the OEM ones. The wheel shop showed me how once put thru the wheel, they only go into the hub 3 full circle turns (by hand). Both the guy and I thought it's way too little threading into the hubs. I called the CA place and they're going to send me some longer lugs. Just wanted to throw that out there, since it may be the cause of some of this. The wheel is on tight to the hub.

Thanks again,
Paul
(Cintoman)

Cintoman

Bump....

Luke, if you have a chance, I posted answers to your questions, plus asked a few more questions.

Thanks again for yours and anyone else's help.

Paul
(Cintoman)

Luke@tirerack

the wheel dimensions have no effect on alignemnt angles

the air pressure placard on a MB product leans heavily towards ride quality which is in direct conflict to what you are looking for .... lowering the rear will help the car rotate faster which in turn will make it handle better

the Pilot Primacy is an asymetrical tire and is absolutely marked with the word "outside" on the sidewall ... your tires made be mounted incorrectly which could lead to a vague feel

lug bolts shouls have a minimum of 6 turns of engagement

Cintoman

Hi Luke,

I thought about that (the placard pressures would favor comfort). Thanks for the confirmation. Well, yes..I did confirm that the tires do have the "outside" written on them. In checking on my unmounted rears tires, I did notice something strange, which maybe you might be able to clear up for me..... I was under the impression that the thread pattern on an assymetrical tire should be going the same way for each side. In other words, wouldn't an assymetrical tire have a right tire and a left tire? So that if there's a V pattern, the V should be a V on both sides, and not an ^ on one side?

With my unmounted rears for reference, if the "outside" is on the outside of each tire, the thread pattern is flipped around for one of them. I'll take a pic and post this in about an hour after returning from lunch. I'll also take a pic of the fronts because I think they're like that as well.

I had thought about getting a 235/45 R17 size (or maybe 235/40 R17) for my fronts to maybe improve the turn-in. My concern with my existing Pilot Primacy's is that the size is for a measured wheel of 7.5 inches. Whereas now, my front wheels are 8 inches wide, which would make the measured wheel a 235 series tire. Is this correct?

And would changing the wheel sizes mess up the ESP, Traction Control, speedometer?

Thanks again Luke !!

Paul
(Cintoman)

Cintoman

Ok, I took some pics of the rear unmounted tires and the front mounted tires. I also confirmed that the rears were oriented so that "Outside" was facing outside. I then confirmed that "outside" was showing up correctly on my front tires. But, as you can tell by looking at the pics, the pattern is "opposite" on one side of my car.

Here's the details of the pics:

Front tires were take in front of the front bumper, looking back
Rears were taken from the back of the car, looking forward (as if I was looking at the rear bumper.

To me, it looks like the front right is the correct way (to disperse water away from the middle)

Thanks again Luke !!

Paul

Cintoman

Luke...still over there in South Bend? I had some answers to your questions, plus some more questions and a few pics, if you wouldn't mind taking a look at.

Again...thanks for your help.

Paul
(Cintoman)

Luke@tirerack

sorry, been buried last few days ...

The tire orientation in the pictures you posted is correct. while it may look like 1 of them is rotating in the wrong direction I assure you it is not. There is only 1 part number for each size and no left or right side designation.

as far as trying to get better turn in and the 235 option it wouldn't really give you waht you want on the OE 17x7.5 wheel as minnimum wheel width is 8.0"

in order to truely achieve what you are looking for it's either

shave the tread down to reduce tread squirm
buy higher performance tires with stiffer sidewalls
buy larger wheel which would facilitate use of shorter sidewall tires

Cintoman

Hi Luke,
Sorry about the contstant questions. But here was my OEM tire/wheel setup which worked/handled beautifully:

OEM 5-spoke wheels that come on the C230

-- Front: 7.5x17" with Michelin Pilot Primacy 225/45 R17
-- Rear: 8.5x17" with Michelin Pilot Primacy 245/40 R17


Now, here's what I have on the car:

C55 AMG replica twin spoke (5 spokes)

-- Front: 8x17" with the same Michelin Pilot Primacy 225/45 R17 I had on in the front before (note, these replica wheels are 1/2" wider at 8" versus my OEM fronts which were 7.5")
-- Rear: 8.5x17" with brand new General Exclaim UHP 245/40 R17.


So now, because the wheel width is 8" (1/2" wider), the front 225/45's look a little taller on the sidewall, because they are not being squeezed/bulged like they were with the narrower OEM 7.5" wide wheels. Looking at the tire from the side, the tire sidewall is at about the same vertical plane as the outermost edge of the wheel lip. Whereas when they were on the OEM 7.5" wheel, the sidewall would bulge out a little bit more than the edge of the wheel. I put my MS Paint skills to work and attached a quick pic of how it looks.

I'm thinking that putting the OEM 225/45R17's on an 8" wide wheel (versus the OEM 7.5" wide wheel) changed it's section width.

Looking at TireRack's Tire Specs page, it says: "Because a tire's section width is influenced by the width of the rim upon which the tire is mounted, the correct industry assigned measuring rim width for the tire size being measured must be used."

So it lists a 225/45R17 tire size should go on a 7.5" measuring rim width, which it did on the OEM wheels. But now that I have 8.0" wide wheel, TireRack's chart doesn't show what size should go for this.

Because of this 225/45 tire on a 1/2" wider wheel, I think this is what's making the steering feel sloppy. It really does feel like I'm riding on major underinflated tires. Just moving the steering wheel left and right about an inch, causes the front end to float bigtime.

Which is why I was thinking that a 235 series tire would be better compatible with my new 8" wide wheel. And if that would work, I'm not sure if I should get a 235/45 series or a 235/40 series?

Would this work, and would this mess up the ESP/brake assist/ABS/speedometer?

Again, I can't thank you enough for all your advice.

Thanks,
Paul
(Cintoman)

ClayMan

Possible placebo effect?

Cintoman

Definitely not placebo. Nearly careened off an off-ramp a few days ago going about 45mph, which I used to take at 60mph with no problem.

Found another posting with a similar issue here: https://mbworld.org/forums/c-class-w203/214382-steering-feels-funny.html

Difference is, the OP replaced his stock 2005 C230 OEM's with C55 ///AMG take-offs.

I was thinking about doing the same thing (buy C55 wheels and mount them on my car), but if the handling is going to be as horrible as the OP's, then

I'm still thinking a 235/45 or a 235/40 series tire might help.

Suggestions?

Cintoman

again for further assistance. Please see my posting #10, as I have more info in there.

Thanks again Luke.

Cintoman