On my 2008 XKR with 20 inch wheels, I just replaced Dunlop tires with Continental Extreme Contact DWS. My initial reaction is they are much quieter than the Dunlops. However, I had them installed at Discount Tire and there is some vibration at 50 MPH which leads me to believe they were not properly balanced. I noticed that Discount Tire used several small stick-on weights instead of a few larger ones that were on the wheel with the Dunlops. I think I read somewhere on this forum that many of the shops have troble balancing these larger wheels and tires. Can anyone give me some guidance here?

 

Mine has the 20" wheels on it. I have replaced the tires and had no problems with the balance. Now my tires do get flat spots from sitting but they usually work out in a couple miles or so. Sounds like they need to lick their calf over again and balance them right.

 

Doesn't everybody use stick-on weights now? Sounds like they just need to re-do them. 20" wheels should not be hard to do - it's a pretty standard size these days on all sorts of vehicles.

 

James, I agree with the guys below, just take car back and tell manager they need to be redone, not balanced right. They should not have a problem redoing it again. Tire size does not matter, someone just did not do a good job.

 

some discount tire places only have/use a regular dynamic balancing unit; other stores also utilize (for a $5-$10 per tire upcharge) a road force balance system, which is much more appreciated by the xk's suspension...go to any Discount Tire for a re-balance, but call first to make sure they have the nicer machine.

 

XKJames: I had the exact same problem you had with your new tires, and it was with Discount Tire (one of their shops). Here's what I discovered:

* With new tires, the balancing could be done poorly;
* One of the sick on weights may come off;
* The biggest culprit, and what happened with me, is when they put new tires on they use a soapy solution on the inside lip of the tire to make the tire easier to get on the wheel. They the balance the tire on their machine. Then when you drive off and put a good deal of torque (eg rotational force) on the tire the inside lip "slips" on the wheel slightly. This may happen several times until the soapy solution evaporates through normal driving. Once the tire is set and doesn't move anymore, the balancing should *stick*.

This happened with my Nitto 555's on my 02 XKR 100.

 

Slipping wheels on rims was pretty commonly known on the Mustang Cobra websites I perused years back. Should always drive new tires pretty mellow for first few hundred miles till the release agents wear off. 20's having such low profile rubber, are much more difficult to mount and there will be a tendency to lube heavily to avoid wheel damage. Hard to have it both ways. I'd suggest you call them, tell them issue, and drive tires 1000 miles before returning to let tires break in etc. Then you will get a long term balance.

 

I don't know if my situation relates to the OP, but I also have 20" wheels and notice a vibration at 70 mph. My local dealer was having a "courteous" inspection day and they told me that all 4 of the wheels were bent. They said this is common with low profile tires hitting pot holes. They suggested that I could get them repaired without replacing the wheels. Car has 67,000 miles - original wheels, not tires.
Anybody have any comments it would be appreciated

 

Unfortunately, your dealer is correct. The 20 inch rims have so little sidewall height that bending the rim is very easy to do on a pothole or other road imperfection.

FWIW, all my wheels were out of balance, and badly balanced at that (too many weights, some offsetting others, etc.). My vibration started at around 60MPH. I had my tires all rebalanced at a local shop that has a Hunter GSP9700 which not only measures road force, but detects where your wheel spokes are and positions the weights behind the spokes so they are not visible. Isn't modern technology great?