Hi guys,

My car is at the dealership and they are not sure what to do.

Here is the situation.

I bought a second set of rims from a guy on the forum who passed them off as OEM but they are actually replicas. Didn't find out until the dealership just called me and told me the rims are a not the same width.

What a I am doing is taking the front 5 spokes my 06 came with and pairing them with the front rims from my "replicas". THis allows me to put 4 245 18 inch winter tires on the car.

Now here is the question:
The dealership does not know what configuration to put the rims on the car.

Scenario 1: Replicas on the rear factory on the front... so the same rim width/offset opposes each other

or

Sceario 2: Relicas on the passenger side and OEM's on the left

Both are 18" I am not sure if the replicas are wider or narrower than the factory service tech didn't know. I asked...

Anyway they are waiting for me to tell them what to do.

I think its best to match rims front and rear ensuring the center of car to center of tire matches per "axel" humour me on that term.

Your thoughts would be greatly appriciated espicially if backed up with some theory!!!

 

If anything I would pair the wheels together on the front and rear of the car. The replicas match each other right?

 

like I posted i your other thread:

not really what you are asking, but I'm not so sure the "nannies" are going to like having the front and rears the same diameter when stock they are different.

You want the same width on the front OR on the back. I would be a little concerned if the "dealership" didn't know this...lol

 

Not to mention if yuo run 18s in the back the diameter needs to be within 5% or it will throw a code. If you run the same tires from and rear you may have issues.

 

yep, that's what I mentioned above.

 

IT didn't give me any code isues this morning but I never got over 50 mph.

Does the code shut down the car or just request to take it to a dlr?

 

Maybe I'm missing something but...

Obviously the replica set needs to paired (2) together for the front OR the rear.

If you are asking if you should put them on the front OR the rear - then we can't answer that without know the offsets. If you have no way of telling us the offset, then pick a configuration (you have a 50% chance of being right the first time), mount the tires and then put the wheels on the car. See if it looks ok. If so, have a nice winter. Else, switch them, and have a nice winter.

 

The replicas will be heavier and probably not as well balanced so I would put them on the rear. Good luck.

 

All 4 tires the same size will cause all kinds of problems with Active Handling and Traction Control. The rear wheel/tire needs to be aprx. 1.3 inches larger in diameter for the electronics to work.

 

do yourself a favor: get the right wheels and stop fudging around with these wheels. chalk it up to a learning experience, a costly one. but the more costly one might be when your car becomes slightly uncontrollable because of these odd wheels.

and while you're at it, take your car to another dealer if they're suggesting it's a good idea to put wheels on the same side of the car. unless that's your idea, that's the most "off" thing I've heard about wheels that are different size/widths.

no idea where you live but even with dealers closing, there's got to be more than one...I hope.

 

The tire diameters causing codes to be thrown would be just a nuisance to me. Whether the different width rims were sorted side to side or front to back would be of no concern to me. The thing that bothers me is running 245s front and rear vs 245 front and 285 rear like the car is designed for. The handling balance of the car is set up with the 245/285 combination to give slight understeer at the limit under steady state cornering. By using 245s in the rear, you've upset the handling balance and now the car will oversteer at the limit under steady state cornering. The really bad thing is when you have a transient like a sudden steering input much like would happen in an emergency avoidance manuever on the street. You'll spin like a top and all the nannies in the world won't help you. Wet/slick roads will only ampilify the affect. I can understand how a person would make this mistake as I did a similar thing when I was much younger with nearly catastophic results, it was pure dumb luck I was able to hang on to it without hitting anything or anybody. (I drove very slowly home feeling very stupid and changed tires immediately and I've never made that mistake again.) I can't understand how the dealership could be so stupid to put 245 tires on the rear and put your life at risk along with anybody else close to you.
Here's a link to some winter tires with the proper size for the rear:
http://www.tirerack.com/tires/tires....(Y)&minLoad=LL
Spend the money and get the correct size tires on the rear, the person you don't hit will thank you for it.

 

Absolutely correct.
Everyone I've ever talked to at dealers or tire shops don't know anything about vehicle dynamics. You DON'T want to decrease grip at the rear.

 

REPEAT; 245/40/18 Front and Rear will screw up your active Handling and Traction Control. The Electronics of the C6 must have a bigger diameter tire/wheel in the rear. You'll do more than "throw codes", the computer will go nuts trying to balance rotational speeds between the front and rear.

If you have to go with 18" X 8.5" wheels front and rear try using close to correct staggered tire sizes. I suggest 265/40/18 rear and 225/35/18 front (if available). The rear 265's are a little too wide for the wheel and the front 225's are a little too narrow but the diameter difference is close to stock. Your speedometer will be off but the A/H and T/C should still work as designed. No Codes, No Limp mode and hopefully acceptable handling.

Use the calculator below to find stock wheel/tire size and for suggested replacement wheel/tire sizes. Remember that you are limited as to what tires fit what wheel width as well as what diameter difference is required for front to rear balance.

http://www.1010tires.com/TireSizeCal...?action=submit

 

I would put the widest width wheel on the front of the car. The reason is the tire diameter would be a tick smaller. Some cars have issues with running the same tire sizes, other don't. Look at the T1 guys they run 315 all the way around.

The distance between the edge of the wheel and the mounting pad, is called back spacing.

Randy