E-450 Cupping tires
I have a 2004 E-450 V10, camper 23 feet long.
I had to replace the front tires after 34,445 Kms (21,400 miles). I bought new MichelinX, had an alignment done and now I've got cupping on my front tires. Odo is 65,413 Kms (40,600 miles). So the new tires only have about 31,000Kms (19,000miles). Tire tread is 12/32 on both tires.
Is this normal: i.e. to only get 33,000Kms (20,000 miles) on these tires before having to replace them for whatever reason? Rear original Michelin X tires are still excellent with 9:11/32 and 11:9/32 tread left.
I noticed the problem about 1000Kms (600 miles) ago when I started to get steering wheel shake at about 85 to 95 Km/h ( 50 to 60 mph). I was in the Yukon .. beautiful place .. but scary place to have a break-down :-))
What causes cupping? How do I prevent this?