2001 Excursion, 5.4L, Rear Wheel Drive - Can poor shocks cause tire cupping only on inner and outer edges of tires (all 4 tires). Center of tires looks great. I have the tires rotated every 5K miles and have the alignment checked every 10K miles and toe adjusted if necessary. Caster and camber are always in specs. Put new shocks on vehicle when tires had about 40K miles on them. Noticed cupping at about 60 K miles. Had to replace tires at 90K miles because of cupping and noise. Replaced the shocks (same brand) when I replaced the tires. However, I am concerned about the possibility of the new tires cupping The old tires had enough good tread in the center of the tires to go at least 150K miles if the edges had not cupped. Please advise, I don't want to repeat with the new tires Thanks!

 

sounds like an alignment issue to me... I would have that checked, most places will do it for free. Poor shocks will typically cause flat spots all the way across the tire. //// from hopping. could also be loose/worn ball joints.

 

Have some one look at the idler arm for wear. That was a problem on my 2001 F150, and a new idler arm fixed the problem and saved my new set of tires.

 

It sounds like you've covered your bases on shocks and alignment. It's pretty unlikely that shocks would cause uneven wear on both edges. This sounds more like an underinflation issue than anything since it does it on the rear as well as the front. What kind of pressure do you run in the tires?

 

Thanks for the reply. I suspected in may have been an under-inflation issue. However, I put 63K miles on the original load range D tires without any cupping problems. (However, Firestone replaced the tires due to a tread separation issue.) The sticker on the driver side door post stated: For maximum comfort when carrying 6 or less passengers inflate front tires to 38 PSI and rear tires to 45 PSI. The load range D tires were replaced with load range E tires and I used the same inflation pressure until after the cupping appeared. At that point, I upped the inflation to the other "not so comfortable" pressure recommend by Ford: Front - 45 PSI; Rear - 55 PSI. However, if under-inflation was the problem, it was too late to correct the cupping once it had started. I am now running 45 and 55 on the new load range E tires. I just want to cover all bases and be sure I haven't overlooked anything. I don't want to have premature wear on another set of tires.

 

I'd say you're good to go. Just keep an eye on your tires, especially the fronts and make sure they're wearing evenly. If you notice the outer edges wearing excessively front I'd bump them up to 50 or 55 as well.

I'm not surprised the Firestones wore well for you, those were some of the best tires I've ever seen for treadlife regardless of pressure. Did you happen to get Perelli Scorpions out of the Firestone recall? If so, I'm also not surprised you had wear issues with those.

 

My tires were not a part of the recall. I had an issue where several of the tires started showing signs of tread separation and, the Firestone store manager said that load range D tires were the problem. The store manager used his discretion to replace the tires with load range E Firestone tires. The wear characteristics have been great. The combination of the wear characteristics and the great treatment that the local Firestone store gave me made a loyal customer out of me.