GunNut

I noticed a lot of bouncing and rattling at the rear of my runner and finally checked out my tires. I saw that the center of the tires were bulging out more than the sides. Is this what you call cupping? I'm not sure how this happened.

I've changed out the rear suspension with downey's spring pack and the doetchtech shocks are new. Only about 300 miles or less on both parts. This was all done before this happened to my tire.

Anyone have an idea how I could fix this or what could have caused this?

callmej75

My swampers did the same thing...I aired down to 30lbs and ran them til they went bald....which was no time.

Hiridentoyguy

overinflation?

GunNut

I thought about airing them down too but know that it won't last long. Hey J, how did they ride after you aired down? Rough? Bouncy?

The good thing is, I called Interco and they said if I take photos of the tires, and can justify the defect, they will replace them. I just want to know why it happened to begin with, so i won't make the same mistake.

I checked the air on them this afternoon and they were right... give or take.

callmej75

My swampers always rode rough. Especially on a cold morning. Once they warmed up, they got less choppy on the pavement. Its the nature of the swamper...

kyle_22r

if you buy swampers and expect a halfway decent ride you're nuts! they're not bad in smaller sizes like 31" and below, but above that and the flat spot problems and all the other quirks of bias tires really come out.

GunNut

I've always known that they ride a bit rough, and I'm ok with that. I'm also aware that they need time to warm up. Again I'm ok with that too.

I just don't understand why the center on some parts of the tire bulged. I mean, the tire is literally lop sided. What's even worse is, it's clearly visible. I don't know if it's something I did.

Kyle, so you mean to tell me that issues like this just happens with tires bigger than 31s? If that's the case... that sucks! lol. Do you think it's a manufacturing issue? Oh by the way, the tires I have aren't bias, they're radials. Does that make a difference? I'm currently running 265/80/16s.

Has anyone had this problem?

callmej75

I had the same problem...like I said...I aired down to where the tread looked flat to me. Somewhere between 28-30psi. They still looked a little bulged in the center...

bruzer1123

My brother-in-law has the same size tires on his jeep-they don't seem to have the bulging issue...but I don't know how many miles on them. Can you post pics of what the tire bulge looks like?

AH64ID

Aired down to 30?? WOW what were you running them at?? Thats really really high. I have had two sets on swampers, the first a 32x10.50 I could run up to max PSI (50) but they wore flat and were on the designed rim width, and were radials. The only time they went to 50 was long road trips, around town it was 25-30. The second set were 33 Bias ply, and the most I ever had in them was 26, usually 22 on road and 10 offroad. The couple of times I had them at 26 was on long hwy trips with 500 pounds of camping gear, on top of my 250 lbs of tools and junk. They just dont need that much air, and most bias are only rated for 30-45 lbs...

Your tires will ride better, and smoother at the propper psi. The way to determine the propper psi it to use chalk and use as little air as possible to get the tread to ride flat. It will take a ton less than you think. This will also allow the bias plys to warm up faster, thus a smoother ride. And the tire isnt overinflated and too stiff. I think you will find they last longer at a lower psi, the propper psi. My guess is even at 30 for callmej75 was too high, and only the center wore, causeing them to go bald really fast.

Like was said smaller swampers, and radial ones, can go to higher pressures.. but bias ply need to stay low. Each rig is different, play with your pressure to find the correct one, dont just guess its 30, or 35, beacuase its probally lower.

GunNut: I just noticed your size and tire... Play with the pressure just the same, you may be able to get a few more psi than a comperable size bias would, but thats a very stiff tire it wont take much to support your truck. And what size rim do you have it one, and what pressure do you normally run?

95SASMudRunner

also see about checking your alignment sounds like your tires could be toeing in/out also know that you have to rotate swampers regularly

GunNut

I'll go ahead and check for pressure. I've only had these tires for a total of about 300 miles.. it's been mostly in the shop. Had to replace severals parts to keep her going.

My alignment is a bit off right now, and there is some toeing. I've been putting it off since I'll be adding to my suspension. This is part of the reason why I haven't driven it too much. Like I said.. total of 300 miles... if that.

John - I'm running on about 30 PSI right now. The tire says that it should be ran at 50 PSI cold. How does that work? Am I ok at 30? Or should I put more air?

I'll try all that you kind folks have suggested... wish me luck.

Feel free to chime in if someone has feedback or experiences they'd like to share.

AH64ID

50 psi cold is probally for max weight, thats a D rated tire you are no where near max weight. Less air is most likly what you need.. better tire wear, better ride, better traction..... as little air as it takes to run a flat footprint.

GunNut

I'll try going lower than the 30 PSI I have in there now and see how they run. Do you think it's safe? I was thinking maybe 25 - 28?

AH64ID

My BFG Muds are never above 26, and thats only when loaded. Around town its 18 rear and 22 front. Yes I think its safe. But I still moniter them for heat, every time I stop, and watch the wear pattern. My 285's are always at about 20 rear 24 front.

For the tire you have its rated at 3085lbs at 65psi. Your truck weighs about 3800 pounds, probally 2000 front 1800 rear, give or take. So for a good starting pressure 3085/65 = 47.5lbs per psi. 900/47.5(rear) and 1000/47.5 gives you a rought start of 21psi front and 19psi rear.

Start there, go a little higher for long highway drives. Since you said you dont dive it much you will be able to try different pressures before long drives. Drop to those pressures... see how it looks, drive around the block look at how flat the tread it. Use some chalk and make a line, drive 50 feet straight, get out and see if its wearing even, if its all gone drive a shorter distance. Once you get a good psi keep them there, on little longer drives and 2-3 psi if empty, more if heavy. Always feel your tires when you stop on long drives, they will be warm, but hot is not good. Tire pressure on large tires, espically swampers, is not set and forget like cars. You have to taylor it to your vehicle and go from there.

Since you have the proper rim width for the tire you will probally be able to run a little higher pressure that you would with say a 16x6 or 16x8, but watch it.

But lets see some photos of what your talking about... and get that alingment too.

gonzo

I have tsl radials on my runner. 33X12.5X15 on 8" rims
They are wearing and ride great. I run 35psi and rotate them every 3k miles when I do the oild change. When I rotate them I bring the 2 rear straight up to the front same side. The front I bring to the rear and cross. In other words the right front will go to the left rear and the left front goes to the right rear.
Mine are wearing great. No cupping at all. They have been on the truck a year and guessing about 30k.

GunNut

Great advise John.. Thank you! Once I get home today, I'll snap some photos before the sun goes down. That'll at least show what I've been rambling on about..lol.

Thanks everyone!!!!



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GunNut

So I air'd down my tires... 30 PSI in the front and 25 PSI in the rear and... IT WORK'D!!!!!

I mean, you can still see that the tires are a little cupped but the ride has improved big time!

I'll ride on them all weekend and see if that's the cure... hopefully it is.

Thanks everyone!

AH64ID

good to hear...

jjrgr21

hopefully someone can help me, on a tire issue--E rated 10 ply tire on a 4 door taco what kind of pressure should i run, i know 80psi is for towing and i dont tow. so should i stick with the door stick recommended pressure of 26 and 26, or what? i've never had a 10 ply.

thanks to all