My current vehicle is a 2001 Ford E250 with twin-I-beam front suspension. Issues removed from discussion (proven good) are wheel bearings, upper and lower kingpin/spindle joints/bearings, shock absorbers, tie rod ends, steering box, tire inflation, and rabid chassis weevils.
I’ve been running Cooper tires for almost 20 years now, and have never experienced this problem: the first pair of Discoverer LT 245 75-16 (load range E-10 ply) began to develop a vibration ~35-42 MPH after they’d been run for <10K miles. I stopped at another dealer than the one from whom they’d been purchased, and when the tire tech spun them with weights on, they showed being off by several ounces. Weights were removed, tires were rebalanced, and although the problem was lessened, it wasn’t gone.
Six months later, at 40 MPH they’re shaking my fillings out. An odd wear pattern is also noted- each little contact spot of the tread is higher at the point where it will contact the road than the trailing edge by 1/8". Visit to the original dealer, and they tell me that I’m not rotating my tires with sufficient frequency. Hunh? I’ve never rotated more frequently than annually, and never experienced this.
They also spoke of this being a problem with “open tread” tire designs, as opposed to “closed tread”. They asked me what my driving habits are (80% interstate and limited access highway), and said I shouldn’t be using an open tread design. Well, shouldn’t you have asked that question a year ago when I was buying sneakers?
Anyway-what’s the straight dope on open vs. closed/continuous tread tire design as pertains to wear, and is rotation every 15K miles insufficient?
I got nuthin on the open vs closed tread design.
But I can tell you that some tires will go out of balance in a very regular manner, which can drive you the driver nuts.
Here are a couple of things you can check
Jack up a wheel, support the truck on a jackstand. Rotate the wheel, and observe the edge of the tire (looking across the tread). Does it run true, or is there runout? Excessive runout can give you a hell of a vibration. IIRC 4/64" is the limit when I was selling tires (Back when dinosaurs roamed the earth)
Pull the wheels and have the tires checked for balance. It is not unknown for the belts in the tire to shift, causing the balance to go bad. I had a set of Badyears once that required a rebalance every 5K. I hated those tires.
At my fathers store we recommend people rotate their tyres every 5-10000 km even if they do it themselves. I can’t give a reason why so often though.
In my experiece for mainly highway work you would want a closed (solid outer rib) pattern. Why this works better I don’t know, but it does, it could have something to do with the way a tyre flexes as it rolls round, a closed rib is going to always be in contact with the bitumen, an open rib won’t be.
I should probably mention that tyres have grooves across, and all the way around, by ‘rib’ I mean a section of tread inclosed by the grooves going all the way around.
As to why the dealer didn’t try to change your mind? Just a guess, but you’ve been using Coopers for 20 odd years. You probably went in and were very sure of what you wanted. If he had started talking about open and closed rib designs and tried steering you away from what you had been using for all this time do you think your BS meter would have gone off?
It is possible that out-of-balance wheels led to some deformations in the tires. Now that the wheels are balanced, the tires still are far from true and are just getting worse.
Got a hazzard warranty on those tires? Might be a good time to accidentally reverse over some spike strips.
Cupping is usually a symptom of improperly inflated tires. If you’re showing more wear at the center then the tire is over inflated, more wear at the sides could indicate under inflated. Its pretty much impossible for cupping to form due to bad alignment.
I have a 91 Ford Ranger with 30x9.50 Dunlop Mud Rovers (a very open design). Second set, actually, because the first set became so screwed up after about 35K miles that I had to replace them. They were cupped, and had high and low spots at different points along the circumference of the tire. I rotated and balanced them about every 10,000 miles. The second set gets rotated and balanced every 5,000 miles, if not a bit sooner. No problems yet, though they only have about 12,000 miles on them.
In between the two sets of mud tires, I had a set of BF Goodrich All Terrrain tires. They lasted about 50,000 miles, and they evetually developed odd wear patterns and then balance and vibration problems. They were not as open a tread pattern as the mud tires.
The best set of tires I ever had on the truck were a set of Michelin LTX AT’s, that lasted 110,000 miles and wore perfectly.
The truck has over 300K miles, so I’ve gone through those tires and two sets of Firestones (worst of the bunch). I love the traction that the full mud tire gives me so I just put up with the very frequent rotating and balancing. I think 15,000 miles is too long. Especially on a truck, where the weight distribution front and rear can vary quite a bit during normal use.