Air down for on-road?

Trebissky

Active Member
Joined
May 16, 2005
Location
Durham, NC
Just wondering... with 31's on my Jimmy, it rides so rough my wife doesn't like to go with me anywhere in it. Would it help at all to reduce the pressure to maybe 25 psi instead of 32, to make them a bit softer? Or do I just need to get used to being jolted going over RR tracks and such?
 
It will ride better but you'll feel more roll and get worse gas mileage. I keep mine at about 28 for the ride quality and just put up with the roll and mileage.
 
Yes, it will make a difference. The ride will be nicer, but there will be slightly more lean in the corners. It could possibly affect your gas mileage, as the lower pressure creates more rolling resistance, but i doubt 7lbs would really make a noticeable difference in the mpg.

Just experiment around with it a little. No harm in that.

PS I run my toyota at 12-14lbs on the street...rides like a caddy.
 
Thanks, I'll give it a try and see what happens.
 
How bout checking the suspension or changing the shocks? What are the sidewall ratings of your tires, C/D/E?
 
Firestone Destination M/T, load range D.

By the way, how much should those "rattle" on the highway? I just had them rotated, before I was getting a little vibe over 60mph, now that the rears are on the front, it shakes a lot more. And could that be just because they aren't balanced right? I asked a guy to balance them once, he said because it's so hard to do with 31's it would be a waste of his time and my money to even bother.

Which made no sense to me, but I figured "he's the expert"...
 
(Shocks & suspension seem to be working normally.)
 
Trebissky said:
Firestone Destination M/T, load range D.

And could that be just because they aren't balanced right? I asked a guy to balance them once, he said because it's so hard to do with 31's it would be a waste of his time and my money to even bother.
Which made no sense to me, but I figured "he's the expert"...
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Load range D on your S-10 is defintely a stiff tire. Should not be a problem for you to air down a little.

Yes - it can shake because they aren't balanced right.

Unless there is a defect in the tire or rim, there is no reason they can't balance a 31-inch radial MT. I hate it when tire places make statements like that. I have 33-inch radial MTs that ride real smooth, don't shake at all.

On the other hand, I have some 33-inch radial AT's that shake because they are a crappy brand and one is defective, and can't be balanced without pad-balancing.

Also, if your tires are worn weird, they will shake no matter how well they are balanced.

I suggest you contact "Lee" on this board and have him take care of your tire balancing at Monro in Briar Creek shopping center. Excellent work.
 
Yea, there should be no problem what-so-ever balancing 31's. Unless they aren't round, they may take a lot of weight, but they should still balance out. And that guy, obviuosly ain't no expert.
 
With the IFS, and a MT tire, without it being in perfect alignment, you can expect the tires to chop, which then give the rattle you speak of. This is even more noticeable if the tires are run in the opposite rotation from which they've been wearing.

32 pounds of air in a tire on a S-series Jimmy. WOW! I never ran that much air in my K5. I'd say run about 25 in the front, and 20 rear. That'll give the best ride quality, but will hurt the handling, but the tires themselves should last longer due to the entire tread being in contact with the road.

He can't balance a 31" tire. He sucks at life, and should not be in business.
 
I run 20 psi on my 31MTs for the Taco. Anything higher wears out the centers
 
Puma297 said:
i've got a buddy with an FJ40 on 38's and he runs like 4 PSI on the street to combat his death wobble. Yet no sidewall bulge. :confused:
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Yeah, and your buddy is asking for trouble. Just because the sidewalls are stiff enough to hold the truck up when they're that underinflated, doesn't mean that they're not getting hot.

He'd be well off to address his suspension problems before he has blowout problems on top of that.

Something in the high teens might be okay, low 20s, etc.
 
I suggest you contact "Lee" on this board and have him take care of your tire balancing at Monro in Briar Creek shopping center. Excellent work.
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Is that the Walmart side or the Target side of 70?
 
32 pounds of air in a tire on a S-series Jimmy. WOW! I never ran that much air in my K5.
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That was normal pressure on the S10 pickup I had before this one. But then, it had 14" tires.

On these 31's, the tread seems even to me, still square on top. But when the ones in front were in back, the wobble was there but not as bad. As soon as they were switched, the wobble increased... and is about the same, now that I think of it, as it was before I had them rotated the FIRST time.

I'm curious about this balancing tires with antifreeze. How's that work? Pour some inside, then put em on the wheels? And like another guy asked, how much do you use? And doesn't the stuff eat the rubber? (Never mind. It flows thru rubber HOSES, doesn't it? Duh.)

EDIT: I asked about this because I remembered that the M151 jeeps in the Army all had stencils on the fenders that said TP-25. Those tires seemed about as stiff and hard as these 31's, so I wondered if that would work.
 
saf-t scissors said:
Yeah, and your buddy is asking for trouble. Just because the sidewalls are stiff enough to hold the truck up when they're that underinflated, doesn't mean that they're not getting hot.
He'd be well off to address his suspension problems before he has blowout problems on top of that.
Something in the high teens might be okay, low 20s, etc.
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i agree, i'm not sayin its a good idea. Its a temporary thing anyway but its not a DD, only drives it to and from the trails every once in awhile.
 
Trebissky said:
Is that the Walmart side or the Target side of 70?
Click to expand...

It is in between Target and BJs. Actually attached to the side of BJs. PM "Lee" on this board to get details, before you go over there.
 
Well I finally remembered to drop the PSI a few days ago. They were actually at 35 or above! I dropped them all to just a bit above 25 and the ride is a LOT better!

As for mileage... it wasn't that great to start with, and with gas costing as much as it does now, what's the difference anyway?

I still have that wobble. I'm getting set to swap the tires onto 4 different wheels soon anyway so maybe once THOSE get balanced it'll quit.

Oh, and... I got an old 31" from Mr DIY last weekend and this same guy I told you about put it on a rim and "bubble-balanced" it with no problem at all. It's now my offroad spare. Why he said he couldn't balance the ones on the truck I have no idea.
 
yea- your tires will be fine.. they were just beginning to "cup" with a good schedule of Rotation and Balancing they'll even out just fine. glad you got that spare mounted quickly.

and yea- 28psi sounds good to me as well. later and it was good to meet ya
 
its fine to balance those tires mine where balanced on my xj and they were 37s guy did it no problem
 
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