My wife's car has 18x9 with 275-40's.The outsides of the tires have plenty of tread but the inside of the rear tires is almost bald.I know if it were the front it would be an alignment issue but on the rear I'm not sure what could cause this.Any help would be appreciated.
tire wear on inside rear
- Thread starter stang72
- Start date
19COBRA93
Ford Racing
Pic? Was it on the front at one time? On a solid axle car it's almost impossible for inside tire wear on the rear.
She is at work right now.No, the tires were never on the front.I know I should have rotated them.Yes solid axle.I'm like you never heard of this happening thats why I posted.Thought somebody on here would have the same issue.It wouldn't be that 275-40 is to wide for 18x9 and caused the center to ballon.
19COBRA93
Ford Racing
Well, I misread your original post. By "inside", you mean "center", right? In that case, they've been over inflated. A 275 on a 9" wide wheel is a near perfect fit. The only way the center will wear too fast is from being a little over inflated. Drop the pressure a few pounds, and/or rotate them.
It could also mean they are under inflated. I read a few articles here tire engineers said that the proper air pressure helps tires maintain their shape and stiffness and under inflated tires can wear down the center just like over inflated tires because the low air pressure causes the tire to deform and expand as the g-forces cause the tire to get "stretched" into a more oval shape while driving.
19COBRA93
Ford Racing
I've never seen an under-inflated tire wear the center without also wearing the outside. Over-inflation is the obvious cause.
Engineers from both Pirelli and Michelin would disagree with you.
19COBRA93
Ford Racing
Then invite them in here to actually disagree, and to get their professional opinion on this specific case.
Since that's not going to happen, logic, and a mountain of experience suggests the tires are simply over-inflated.
bcb06gt
Senior Member
My rims/tires from AM had a large sticker on the box saying to adjust pressure as desired as they are filled to 42psi (Nitrogen filled). Yes, I lowered the pressure.
Infamousjim
Member
42 PSI!? I don't see any reason do inflate that high unless you need to seat a bead (But then drop it right afterwords) or did you mean 32?
19COBRA93
Ford Racing
I run my fronts at 45. It's probably so people can run whatever pressure they want without having to find a nitrogen fill station.
bcb06gt
Senior Member
Correct. AM sets them like that so if you want to run less, let some nitrogen out. Never want someone to have to add nitrogen to new wheels.
They came between 42 and 44. I lowered the pressure.
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skwerl
tree hugger
Pressure changes with elevation as well. So 32 lbs for your location might not be 32 lbs at my location. Another reason to overinflate and let the customer adjust the pressure (if they remember or read the sticker on the wheel).
Digital_Synapse
Senior Member
I run mine at 37 all around. Max inflation on mine is 50, I up to 40 for racing to keep the walls from flexing off the rim, lol.
VTXFrank
Obama SUCKS!
That doesn't happen with a Nitro fill. That's why it's required for use in aviation tires. The pressure difference from sea level to 6500' in Denver would be very little. Maybe a pound. Heat and cold also do not affect a nitro filled tire very much. You're more likely to lose pressure due to molecule migration through certain tires/old tires than to lose pressure due to altitude or temperatures.
Norm Peterson
corner barstool sitter
I'm pretty sure that the use of N2 in aviation tires involves entirely different reasons.
6500 feet of elevation difference should be worth about 3 psig.
9" is the minimum recommended rim width for that tire size, which is generally designed around a 9.5" wide rim. Assuming that it's the tire size you want, the wheels really are a little on the narrow side. That, and some tires more than others, can make for greater sensitivity to inflation pressures.
It is entirely possible for a solid axle to have cambers or toes that are not zero. Be careful about making "obvious assumptions". My other stick axle car actually has about -0.5° rear wheel camber (as well as nearly as much toe-in). No, I did not modify it to make it that way (I would never have put the toe-in like that).
Nitrogen still has to obey the gas laws. The only difference is that it comes out of the fill station with less moisture content than what your average regular air source gives you. That affects pressure rise during operation, meaning that the pressure in the N2-filled tire will rise somewhat less. But an N2-filled tire will still show a temperature-caused increase in pressure with driving.
There is some evidence that N2 diffuses through the tire carcass at a slower rate than O2 and most of the other trace gases. But a good "tight" tire shouldn't leak much regular air out, so this is not as big a benefit as the N2 equipment outfits would have you believe.
Hope they didn't charge you anything extra for the N2 fill.
Norm
6500 feet of elevation difference should be worth about 3 psig.
9" is the minimum recommended rim width for that tire size, which is generally designed around a 9.5" wide rim. Assuming that it's the tire size you want, the wheels really are a little on the narrow side. That, and some tires more than others, can make for greater sensitivity to inflation pressures.
It is entirely possible for a solid axle to have cambers or toes that are not zero. Be careful about making "obvious assumptions". My other stick axle car actually has about -0.5° rear wheel camber (as well as nearly as much toe-in). No, I did not modify it to make it that way (I would never have put the toe-in like that).
Nitrogen still has to obey the gas laws. The only difference is that it comes out of the fill station with less moisture content than what your average regular air source gives you. That affects pressure rise during operation, meaning that the pressure in the N2-filled tire will rise somewhat less. But an N2-filled tire will still show a temperature-caused increase in pressure with driving.
There is some evidence that N2 diffuses through the tire carcass at a slower rate than O2 and most of the other trace gases. But a good "tight" tire shouldn't leak much regular air out, so this is not as big a benefit as the N2 equipment outfits would have you believe.
Hope they didn't charge you anything extra for the N2 fill.
Norm
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Norm Peterson
corner barstool sitter
I guess it's possible, but probably under a rather narrow range of conditions. Any tire H rated or higher comes with a cap ply that would reduce the extent to which this would happen.
I do remember tires on go-karts wearing into a rather odd contour, but I think the heavy wear was not quite in the center of the tread. And some of the early belted tires would wear the second rib in at a much faster rate then the ribs on either side of it.
Norm
Mr. Q
Senior Member
hi, i'm threadjacking because i have a serious rear camber issue.
i'm at my wit's end because i can't figure out what is wrong with the rear. the tires i replaced today had worn down to the threads on the inside while there was at least 20-30% tread on the outside.
my 07 gt is lowered with eibach pro, koni yellow, with maximum motor camber plates. i have an adjustable 3rd link as well as adjustable lca's.
what, exactly, creates tire wear on the inside of a solid axle car? i'm game to replace/fix anything at this point.
thanks in advance.
-e
the tire size i run is 255/45/17 on stock rims.
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skwerl
tree hugger
Bent axle?
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