My 98 Ford Ranger started cupping the front tires, both simultaneously, within about 5000 miles. When rotated to the front, the back tires also cupped simultaneously. I suspect a design problem with the truck. Ford, or course, wants to deny that. What is the problem cause?
More likely worn suspension issues, all the way around, on an 11 year old truck. A true design issue would have manifested itself well before the 11 year mark.
Time for a suspension specialist to do a good check on condition of the suspension.
As jayhawkroy correctly stated, a design flaw would have been evident long before this on an 11 year old vehicle, and instead, this is surely the result of worn suspension components. Certainly nobody should be surprised by the possibility of worn components on an 11 year old truck.
This situation can be caused by problems with any of the following: ball joints, wheel bearings, shock absorbers/struts. Since these components–particularly the ball joints–are safety related, I suggest that you take the truck to a well-reputed shop that specializes in front-end repairs.
You know the old saying, “When you lose a wheel at high speed, it can ruin your entire day”.
If you don’t have the necessary front-end repairs done, losing a wheel at high speed can be the result, in addition to ruining at least two of your tires.
Third vote for “Not A Design Problem”.
What you have is an alignment issue - and has been stated, it’s probably caused by something that has been worn and needs to be replaced.
Tire cupping is caused from worn out shocks/struts.
Tester
Thanks for everyone’s response. One problem–the truck started cupping tires within 5000 miles of being new. Also, just had a new set of tires put on, replacing the originals at 43k miles, and had the alignment set by a Ford dealer. The technician checked all suspension points & shocks and gave them a clean bill of health. Settings for camber & caster for front left and front right were within spec before and after new alignment. Ditto for front cross camber, front cross caster and front total toe. Front end was in alignment & shocks OK. Based upon this info, now what are your theories for cupping?
The truck may have a defective idler arm (if so equipped). The bushing may be damaged, allowing the idler arm to change up and down position. This could be hard to detect when testing on the machine (swivel plates). There isn’t enough stress to make it shift position unless the truck is on the road. If you still have the paperwork, and the toe-in has to be reset more than a quarter inch on every alignment, I would be thinking about that strange possible cause.
Cupping is caused by defective shocks or struts.
Out of balance tires (even slightly) can cause worn spots in the tires that may be interpreted as cupping.
Depending on the wear pattern, it’s even possible to diagnose some feather-edging as cupping but feather-edging is an alignment issue for whatever reason.
It’s not likely a design flaw at all and even if it were, after 11 years you’re out of luck.
This issue should have been taken up at the 5k miles mark, not a decade later.
And with some shocks and especially struts, it’s not always possible to tell if they’re weak by bouncing the front end of vehicle up and down. I’ve seen many that passed a bounce test but when disassembled one can easily notice the weak spots in the units.
There is a certain amount of inconsistency between “…the truck started cupping tires within 5000 miles of being new …” and “…replacing the originals at 43k miles…”
I think what you are looking at is Heel and Toe Wear, not Cupping. You can feel Heel and Toe Wear when you rub your hand over the face of the tread. The individual tread elements will have sharp edges - which you will feel rubbing in one direction and not the other direction. Because the individual tread elements will bend as they enter the footprint (causing a rounded edge - the heel) and slide as they exit the footprint (causing a point - the toe), this is considered normal (if not excessive).
Cupping Wear is where one or more tread elements wear faster than the others. It may or may not have sharp edges. When the shocks are bad, this wear pattern will be between once to 3 times around the tire. If it is more than that - particularly if it is over 6 times around the tire- then this is caused by misalignment - typically toe.
Put another way, if you can perceive cupping within 5K, then the tires won’t last beyond 20K. Getting 43K means the tires were not cupping.
BTW, radials tires don’t like more than 1/32nds of an inch toe-in (0.06 degrees) PER SIDE - and typically published alignment tolerances are twice that. So just because the alignment is “In Spec”, that doesn’t mean it won’t cause wear problems.
Another exciting and informative answer!!!