I have a 1999 XK8 convertible and have replaced front and rear Dunlop 5000 Sport 245R17 tires all around twice in 37,000 miles. The fronts wear out on the outside tread on both sides. I replaced the worn fronts, put the good rears up front and put the new ones on the rear. Then the fronts wear out in 4 months and I slide all over the road in rain. Are these the right tires and sizes? i read somewhere fronts should be 245 and rear 255? I use 35psi all around. Alignment is good, motor mounts, Bilstein struts, brakes all good. Mechanic is stumped - Dunlop says warranty no good due to wear.Bushings? ($900 each? and they are guessing - I would rather put on 2 new Hankook Optimos for $125 every 4 months).

 

Sounds like some suspension/alignment problem despite what you've been told.

I'll let others say if the size etc are right - or you can look at brochures.

 

Have you replaced the factory upper shock mounts? If not, they long ago disintegrated, threw off your toe alignment, and are the primary reason you are going through tires so quickly. Look into the Welsh Enterprises poly replacements....

 

+1 on you got suspension issues.

Read my recent post here that covers tire pressures and how to check for worn upper shock mounts.

If you post a few pics of the car from each side and front we could probably give you better advice.

 

+1 with Jon89. I wore out tires same way. Check your ride height. Bet it's an inch low.

John

 

+1 and check out the tables on Rothwell's post.

First impressions, is that your pressures are a tad too high but still not enough to wear the tyres out so fast. I too have a 1999 xk8 with original Revolver wheels, and manual says 245/50/R17 all round. However your car's PO could have switched tyres especially if he wanted the XKR's more sportier feel. Easy to do on the X100 platform and parts are interchangeable. You mention the car slides all over in the wet, so I'm guessing that you're a vigorous driver, and give the car a "heavy right foot." Still that wouldn't explain the excessive front tyre wear.

Strange thing is that your Mechanic is stumped, but excessive outside tyre wear, typically means that the toe is aligned too much in, so maybe go to another alignment shop and make sure the technician sets it toe out (within the computer tolerance).

Another possibility (check the above first) is due to the fact that our cars are old now and probably been subjected to hitting a few potholes in their lifetime. As the mechanic is stumped, a remote possibility is that the rims could be damaged/cracked on the inside and so is not visible when doing the alignment. The tyre change gorillas rarely check the condition of the wheel when they change the tyres. On old classic cars, this manifests itself as steering shakes but balancing the tyres and setting alignment doesn't make it go away, so that's the next check.

Good luck and let us know how you get on.

 

The Hankooks will probably out wear the Dunlops two to one and cost half as much. How many of us actually need hi performance fast wearing tires? Put Hankooks on my Ford Lightning after going thru two sets of Goodyear Eagles in 24,000 mi at $ 1,200 or more a set. Have 10,000 on them and they show hardly any wear.

 

Have new Dunlop sport 5000 245 50 r 17 on rear, the fronts are worn on outside tread. You have pointed out I probably have very low ride height and probable disintegrated upper shock mounts, which I will replace with urethane, check for cracked rims and possible other front suspension items, and reduce psi from 35 all around- which Mida did when they gave me new tires and laser balanced them.. I like the Hankook h426 tires and reviews. Can I put those on the front?.

 

I would not mix tire brands or tread patterns, especially if the four tires are same size could be rotated throughout their life.

 

First when the ride height suspension goes down the toe goes toed out not in and outside tire wear is caused by too much toe in. This is a much less common tire wear than inner. Reason being is because when bushings and other suspension pieces wear they let the suspension respond too much when driving. The natural road force acts upon the suspension to toe it out not in. So inside tire wear is 99% of the irregular wear seen.
Personal opinion:::: Tires say too much toe from outer tire wear. .either they have toed it too far, or their alignment machine is out of calibration and they "think" they have a good alignment

 

It's Midas Muffler and they supposedly use a laser
alignment machine. of course, they also put 35 psi in all tires all around.

 

yeah most shops use leds and cameras, aka lazer. But they all have to be calibrated yearly. At least we do. I would like to see the bar graph printout. And nothing wrong with 35psi. Better than 25