Tires Cupping

[rollinstone]

Last week started picking up a thrumming noise and slight vibration from rear wheels (Goodyear Wranglers P235/75R15s). Ran my hand over the tread and I could feel the irregularity due to cupping...both rears. Fronts are OK.

My tire dealer rebalanced all four tires and cross rotated the rears to the front and said time/miles will tell if that solves the problem. Ifit doesn't the tires now on the rear will develop the same problem. They also stated that it could be caused by bad rear shocks which are OEM and have 95K on them.

I checked the shocks by bounce (1 to 1 1/2) and looked for leaks (none). Do you recommend I change out the shocks anyway? Ford dealer says there's no recommended shock changeout schedule...just go until failure/poor performance.

Or should I wait and see if cupping develops on the tires which are now on the rear?

If I go for a shock change, what's a good brand? Gabriels? Monroe Sensa-Tracs? They're easy to replace. I don't do off-road other than driving to an occasional trailhead over a dirt road or ski trips that involve some snow on the highway.

Thanks loads...you guys are great!

 

[VBVA]

Thats quite a bit of miles on the shocks, so I say go ahead and replace those. Cupping, at least it seems to me, is caused by improper inflation. If the wear is in the center of the tread the tire is overinflated, it the wear is n the outside of the tread, the tire is underinflated. If you want to extend the life of your tires, make sure they are properly inflated, you have a correct alignment and you rotate them every 6000 miles or so...

 

[X~FACTOR]

You definitely need new shocks. Gabriel VST are good for just $25 each. Installation is fairly easy as well. If could spend a little more go for Edelbrock IAS for $70 each.

 

[rollinstone]

I've been real good about maintaining correct tire pressure. My tire dealer says keep them at 30 psi.

I'll go ahead and change out the shocks. Gabriels @ $25? Seems a bit cheap, but, hey, if they work, so much the better.

Thanks, guys!

r.s.

 

[X~FACTOR]

I have the Edelbrock IAS myself but the Gabriel VST have the same amount of praises from members here (I think). So a lot consider them a good buy.

Don't let the $25 fool you. Some say, "you get what you pay for" but it does not apply here.

 

[jimbo74]

monroe sensatracs are good, especially for a mainly street driven X

gabriels are good too

edelbrocks are good too, but way overpriced--heard they were just as good as the gabriels



go replace the shocks, sounds like they are the cause for the cupping

 

[X~FACTOR]

Also, 30 psi seems low to me especially if its mainly driven on the road only. You could bring it up to 32 or even 35 and get some extra MPG.

 

[jimbo74]

anywhere between 30-35 is ok for explorers.....

30 will give the softest ride but worse mpg, and 35 will give a harsher ride but better mpg

do a search for chalk test

 

[Agent_51]

Blown shocks can cuase a tire cupping problem, if the rest of your suspension is good and the tires are balanced then new shocks might cure the problem but at 95k miles on them, you'll probably be doing yourself a big favor for getting new ones anyways. Your ass is gonna thank you when your driving with new shocks.

Anyways, shock are personal preference i think, but ive had a very nice time with my bilsteins.

 

[jimbo74]

bilsteins are nice, just too $$$$$$$$$$$$$

 

[Agent_51]

Originally posted by jimabena74
bilsteins are nice, just too $$$$$$$$$$$$$

Less than edelbrocks arent they? I think the oem replacement bilsteins are like 50 bucks arent they? I have no idea anymore...