Tires cupping

ChevyHDGert · April 18, 2005

The front tires are cupping on my HD.

They are still the factory Firestone 245's and no matter how much air I put in them, they still appear cupped. They've been like this for a while and never worried about it cuz I plan on getting new, bigger ones soon.

Is there a reason for this?

snoman · April 18, 2005

The front tires are cupping on my HD.

They are still the factory Firestone 245's and no matter how much air I put in them, they still appear cupped. They've been like this for a while and never worried about it cuz I plan on getting new, bigger ones soon.

Is there a reason for this?

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4x4's tend to be a bit hard on front tires some more than others (with old Ford TTB front ends being realling bad). Do you rotates the tires to even up the tread wear? If not you should because it will extend usefull tire life and balance out wear too. I have gotten as much as 70K out of a set of tires on a 4x4 but I rotate them about every 5k miles in such a way that it takes 4 such "rotations" before the tire is back to the same position again.

rascal · April 20, 2005

so right front to left rear, left rear to left front, left front to right rear?

snoman · April 20, 2005

so right front to left rear, left rear to left front, left front to right rear?

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You got it, thats the way I have done it for over 25 years.

MS3DALE · April 20, 2005

I always put the left-rear on the right front and right-rear on the left front and move the front tires straight back,been working for me for over 16 years,but like snoman said as long as the tires are moved to all four positions at one time or another you should get excellent wear,I've gotten over 50,000 miles on tires with useful tread still left on them.

Bart2500HD · April 20, 2005

I always put the left-rear on the right front and right-rear on the left front and move the front tires straight back,been working for me for over 16 years,but like snoman said as long as the tires are moved to all four positions at one time or another you should get excellent wear,I've gotten over 50,000 miles on tires with useful tread still left on them.

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This is how the owner's manual says to do it. It works for me. I noticed some cupping too and I rotated mine two weeks ago.

mmmikkke · April 21, 2005

I got 115,000 miles on a set of Michelin XPS Rib's on my '95 without ever rotating the tires. Also never had to balance them (after the original balance). They were smooth as ever, shimmy free, for all 115,000 miles.

That was an example of good tires which were dimensionally stable. It was also proof that tires don't have to cup. And it was also proof that you don't have to rotate your tires, unless you have tires that are out of round, or otherwise misbehaving.

And so you move them around on the truck so that the different spring constants, and different loads, and different suspension dampings, can interact with the imperfections in the tire differently. Result, is that a tire that cups in one spot on the right front will cup in a different spot when mounted in some other location.

Cupping is the result of the tire misbehaving. It could be that every time the tire makes a revolution, it's being 1/16" out of round will load the tire, and unload the tire over and over, by that 1/16 of an inch. Even though the deflection is slight, it's enough to cause some squirm in the tread, enough to wear away part of the tread over tens of thousands of revolutions.

When you see cupping, you have either an out-of-balance condition, or an out-of-round condition, causing this microscopic loading and unloading of the suspension, over and over, hundreds of thousands of times over the life of your tires.

Some repair shops will also claim that bad alignment causes cupping, but they're subscribers to the black box theory, and everything's f'n magic, so don't even try to understand, because they said so. Blow them off. Concentrate on the actual problem.

Worn suspension components can cause cupping, but only because it permits the out-of-round or out-of-balance condition to do worse things to the tire than would have been the case if the suspension was not sloppy. Or if your suspension is fine, and you have this little cupping problem for 40,000 miles, by the time you have worn out the tires, you also have worn out part of your suspension.

I've always taken the factory tires off the vehicle immediately after purchase for this reason. Rather than punish the suspension with a cheezy out-of-round tire for 40,000 miles, take 'em off at the beginning, get a few bucks out of them, put on some premium rubber, and have a smooth ride for 115,000 miles.

snoman · April 21, 2005

I got 115,000 miles on a set of Michelin XPS Rib's on my '95 without ever rotating the tires. Also never had to balance them (after the original balance). They were smooth as ever, shimmy free, for all 115,000 miles.

That was an example of good tires which were dimensionally stable. It was also proof that tires don't have to cup. And it was also proof that you don't have to rotate your tires, unless you have tires that are out of round, or otherwise misbehaving.

And so you move them around on the truck so that the different spring constants, and different loads, and different suspension dampings, can interact with the imperfections in the tire differently. Result, is that a tire that cups in one spot on the right front will cup in a different spot when mounted in some other location.

Cupping is the result of the tire misbehaving. It could be that every time the tire makes a revolution, it's being 1/16" out of round will load the tire, and unload the tire over and over, by that 1/16 of an inch. Even though the deflection is slight, it's enough to cause some squirm in the tread, enough to wear away part of the tread over tens of thousands of revolutions.

When you see cupping, you have either an out-of-balance condition, or an out-of-round condition, causing this microscopic loading and unloading of the suspension, over and over, hundreds of thousands of times over the life of your tires.

Some repair shops will also claim that bad alignment causes cupping, but they're subscribers to the black box theory, and everything's f'n magic, so don't even try to understand, because they said so. Blow them off. Concentrate on the actual problem.

Worn suspension components can cause cupping, but only because it permits the out-of-round or out-of-balance condition to do worse things to the tire than would have been the case if the suspension was not sloppy. Or if your suspension is fine, and you have this little cupping problem for 40,000 miles, by the time you have worn out the tires, you also have worn out part of your suspension.

I've always taken the factory tires off the vehicle immediately after purchase for this reason. Rather than punish the suspension with a cheezy out-of-round tire for 40,000 miles, take 'em off at the beginning, get a few bucks out of them, put on some premium rubber, and have a smooth ride for 115,000 miles.

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This is a very rare exception if this is true because this is not the norm at all on a 4x4 truck. No front end on a 4x4 is that perfect by design and application. My 89 burb has cupped tires just a bit since day one (you can start to feel it with your hand at around 5000 miles) with several tire brands including the Mich's on it now. The alignment is perfect as can be and the truck tracks well and will travel up to and over a 1/2 mile on a good flat striaght hiway hands off without leaving its lane. It still does the same, no more or less 170k miles later. Though cupping can be caused or aggrevatted by worn front ends I have seen cupped tires many many on brand new cars and trucks and ones with new front ends. Cupping is most often cause by chamber and toe combitions that are not matched and tire balance and construct can do it too sometimes and sometimes because of the geometery of the truck front end and it use it is unavoidable in a 4x4 truck. The tires are actually "skipping" a bit in contact area as they roll down the road "erasing" parts of the tread for either a bad tire belt or a poor alignment as mentioned above or because of suspension design and application. When you rotate your tires, extend tire life by changing the wear stress the see in their life to negate any wear problems seen in any one position on the vehical.

MS3DALE · April 21, 2005

I would agree with snoman,I would never not rotate my tires (I rotate them every 3,000miles) and I don't see how any of these new 4x4s could not cup tires in the front.

I have had 8 GM trucks with this IFS front susp.and they all cup (or "feather") the front tires a little. And I'm a fanatic on wheel alignment and I'm always getting it checked.

If you got 115,000 miles on a set of tires and never rotated them then you were definetly very lucky and thats a very rare case of "perfect alignment, perfect tires and perfect balance job"

mmmikkke · April 21, 2005

Like I said, if your tires aren't round (dial indicator, anyone??), you should rotate them.

But know it's because of your tires or wheels that you have to rotate them. It's not your truck!

Wingnut · April 21, 2005

Michelin XPS ribs are completely worthless tires for pretty much anything but the highway, and thereby not an option for the majority of folks. They're designed for mileage, and that's just about it. "Perfect for commercial uses where high traction isn't needed, and high mileage is" according to TireRack.com.

Not-so-good traction in the rain, and "unacceptable" in the snow.

Tire Rack.

They're really not a viable option for most of us.

Don't get me wrong mmmikkke, I'm not trying to argue with you, I think it's great that those tires worked so well for you. I'm just letting people know that they shouldn't just run out and buy them before the next blizzard.

mmmikkke · April 21, 2005

Nice trick. Now the casual reader thinks TireRack considers these tires "completely worthless."

Whatever.

Let's get back on topic.

Wingnut · April 21, 2005

Not trying to trick anybody man.

I'm just saying that the reason that they wear like iron, is because they are hard as iron, and traction suffers because of it.

Just depends on what one is looking for in a tire. It's always a compromise.

I'm not trying to offend anybody, and I have nothing against the tires.

rascal · April 22, 2005

i was cleaning up the barn, we tore it down and built a new one next to it, well any way, I came across the spare of my 88 that burned or my 95 that got stolen. it's one of the orginal equipment tires, goodyear TD?. was a good tire, didn't last long. wander if they still make them.

MS3DALE · April 22, 2005

Yes,You can still get the Goodyear Wrangler TD's,I loved those tires on my '93 and '94 Z71's.(I even ran them in the winter on my '97 Z71 that came with the summer tread-like RT/S's)

I always got at least 40,000 miles out of 'em!