How much PSI?

atreyu · **Joined:** Thu Aug 30, 2007 3:14 pm **Posts:** 23

I have tire size P235 70R16 . the recomendation on the door is 33 and max on tire is 44. Im curious as to what everyone else runs with this size tire. should I put more air in them or keep at 33? Thanks!

renegadekj · **Posted:** Sun Sep 02, 2007 4:05 pm

I run mine from 33 - 35

Guest · **Posted:** Sun Sep 02, 2007 7:09 pm

I've run my Discoverer ST's at 35 since I've had em, and they've got quite a bit of center wear. my next set will probably stick around 31 or 32.

Max on the tire is almost always going to be higher than what the vehicle says on the placard. if you're unsure, keep it at 33. the only thing more air will do is make your tires wear funky and rattle your teeth over bumps.

Big D · **Joined:** Mon Jun 05, 2006 10:08 pm **Posts:** 349

If you check a little more in this section, you'll notice that this topic was covered before a number of times. The sticker on the door jam gives the recommended PSI for a fully loaded vehicule. Since most people rarely check their tire pressures, it is also the one the manufacturer recommends. I run 27-31 depending on how loaded I am. I've gone as high as 40 in the back but that was loaded very heavy.

geordi · **Posted:** Sun Oct 07, 2007 11:15 pm

How much pressure? ALL of it!

No matter what the sidewall max is, if you NO LONGER HAVE THE DEALER-ISSUED GOODYEARS... The door sticker CANNOT be trusted!

Run the sidewall MAX, or no less than 10% below the sidewall max. For any 44 psi tire, that means no less than 40psi. Any lower than 10% below sidewall max on non-original tires, and you are endangering your life with over-flexing and overheating the sidewalls.

Also, if you have changed the OEM tires out for another brand... Well, Mopar didn't test those Brand X tires with the Liberty to their specs, right? They only tested the Goodyears, and that is why they "Suggest" a pressure for the Goodyears. I personally will be purchasing a set soon of BF Goodrich COMMERCIAL T/A tires, and those bad boys are _80PSI_ sidewall max monsters. Do you think they would survive even a few days at 33?

Heck no!

Run the sidewall max and drive safely. Your tires were rated and designed to work at their max pressure by the tire maker. Want a softer ride? Buy a Lincoln or softer shocks.

tommudd · **Posted:** Sun Oct 07, 2007 11:46 pm

Do not run max that is ONLY if you are hauling very very heavy loads, having 40/44 lbs of pressure will only wear out the centers and cause a hard ride!

geordi · **Posted:** Mon Oct 08, 2007 12:24 am

Respectfully, the tire will not wear in the center. You are thinking of old Bias ply or trailer service tires. Modern steel radials have to be WAY overpressured before they will "round out" like that. Oh, for reference: A modern undamaged steel belted radial is capable of holding up to double (if not more) than it's sidewall max without exploding. This is by no means a good idea, but it IS possible. The reason for this is that if someone is inflating, and the chuck gets stuck, you don't want to have the tire burst before they can get the chuck off. But you also don't want to go driving on a tire that full.

Also, tires that are soft will gain MORE pressure from heat expansion than a fully inflated tire, and are more likely to blowout due to their inability to discharge the accumulated heat from a hot roadbed AND the excess flexing.

On all 8 of my vehicles (ranging from a VW Jetta TDI to 2 RVs, an 8-ton chassis and an 11-ton chassis with load range F 22.5" truck tires) I run full sidewall max, and have NO problems with unusual wear or cupping or anything else. Also, I don't rotate the tires anymore. I used to, but since I've started buying directional tires and STILL getting the full wear out of them... Why waste the money?

YMMV, but I'm looking for full sidewall max no matter what I'm hauling. The tires were DESIGNED to run at that level, or NO LOWER than 10% below that level. Anything lower, and you risk tire failure.

tommudd · **Posted:** Mon Oct 08, 2007 1:53 am

geordi wrote:

Respectfully, the tire will not wear in the center. You are thinking of old Bias ply or trailer service tires. Modern steel radials have to be WAY overpressured before they will "round out" like that. Oh, for reference: A modern undamaged steel belted radial is capable of holding up to double (if not more) than it's sidewall max without exploding. This is by no means a good idea, but it IS possible. The reason for this is that if someone is inflating, and the chuck gets stuck, you don't want to have the tire burst before they can get the chuck off. But you also don't want to go driving on a tire that full.

Also, tires that are soft will gain MORE pressure from heat expansion than a fully inflated tire, and are more likely to blowout due to their inability to discharge the accumulated heat from a hot roadbed AND the excess flexing.

On all 8 of my vehicles (ranging from a VW Jetta TDI to 2 RVs, an 8-ton chassis and an 11-ton chassis with load range F 22.5" truck tires) I run full sidewall max, and have NO problems with unusual wear or cupping or anything else. Also, I don't rotate the tires anymore. I used to, but since I've started buying directional tires and STILL getting the full wear out of them... Why waste the money?

YMMV, but I'm looking for full sidewall max no matter what I'm hauling. The tires were DESIGNED to run at that level, or NO LOWER than 10% below that level. Anything lower, and you risk tire failure.

need to do some more reading but I will not argue since you "seem" to know it already. But please read and also maybe even ask at your local tire shop. Max pressure in a tire is not what you run in a tire.

"the pressure listed on the tire sidewall is the MAXIMUM tire pressure or the tire pressure that is required to carry the maximum load of the tire. IT IS NOT the manufacturers recommended tire pressure which is a common misperception"

How much PSI?

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