how low pressure can I keep my Goodyear Wrngler MTR tires on the freeway

I'd like to see if I can keep my tires a bit lower pressure in street and freeway driving to give me a bit softer ride.

How low is safe for this type of driving.

For the record I've got 31 x 10.5 goodyear wrangler MTR LT tires

I thought they were made to ride rough :doh: . I would'n go below 30psi.

what pressure is listed on the sidewall?

I would not suggest it, as driving at lower pressure than what is recommended for long periods of time will cause undue stress and lots of uneven wear in your tires.

Kris

My understanding of it is that the sidewall number is the maximum pressure, not the recommended pressure for you to run. That's why I aired my tires down to ~26lbs/17lbs front/rear on my MJ. (Until I got my spool, but that's a different issue.) It had a nice flat contact patch across the width of the tread. Go-Jeep also has a recommendation on his site for setting pressure, based on cold/hot pressure differences. Do some searches for "tire pressure" and you'll likely find some tips on setting pressure.

Running 14lbs at each corner on the highway causes engine fires, though. :looser:

I run about 30psi in the winter and about 35psi in the summer with my 31 MTRS....they run rough but its bearible, offroad I run about 20psi which gives me a good footprint. I wouldn't suggest too low of a pressure a buddy of mine ran btwn 10-15psi on the highway and it really killed his mpg.

minerjeepguy said:

I run about 30psi in the winter and about 35psi in the summer with my 31 MTRS....they run rough but its bearible, offroad I run about 20psi which gives me a good footprint. I wouldn't suggest too low of a pressure a buddy of mine ran btwn 10-15psi on the highway and it really killed his mpg.

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10-15psi? Wouldn't you want to worry about rippin it off the rim at a sharp turn?

I run right at 30 with mine on the street.

I've always run between 25 and 28, with 33's ands 35's. The correct pressure is what will give you a flat contact patch with the weight and load of your vehicle. Try varying the pressure and look to see if the whole width of the tread surface is touching the road.....use just enough to get full width contact. Too much pressure and the sides won't touch (will wear in the middle), too little and you'll get excessive wear on the outside. I'd bet 28 lbs is what you can run.

The pressure on the side of the tire is maximum pressure for a maximum load.

Agree with Goatman & Matt...somewhere between 25 & 30 will probably work best.

I've run as low as 10# on asphalt (15-40 miles to air up, up to approx 50 mph, 33x12.5 Muds, 5 speed,4.56:1, spool in R) and I guarantee it wears out the tread like nothing else can!

I wouldn't want to think about running extended miles on the highway at trail pressure...kiss that set goodbye...maybe even :explosion:

What preasure is safe?

That depends more on your driving. The tire MTR/LT can handle the weight of a XJ at about any preasure that it will roll at. The tires are made much stronger than what an XJ will ever tear it up on the street.

I've run trail preasures (10 psi for me)for weeks at a time driving on the freeways and never have had a failure due to low preasure. I have even driven on with 5 psi at freeway speeds for an hour once before noticing and it never failed. Now low preasure will wear your tires faster but not as fast a a good JV trail run.

I would air them up to what you like best with some of the ideas above about contact patch. A good way to check contact patch is driving thru water and then checking out the marks left by the wet tire.

Just realize if you need to drive carefully at first to see if the lower preasure and your driving style fits one another. ie. fast driving and low preasure don't turn great!

hinkley

I have to agree with Mark. I've NEVER ran more than 22 psi in my 285/75R16 MTR's. Those tires have about 20k miles on them and are wearing evenly. I'll bet 2000 of those miles were run at 12psi. The tire store put 32 psi when they installed the tires, talk about a cr@ppy ride. I also get a GPS verified 17 mpg on the highway.

Also you can check the heat buildup. When I'm playing with tire pressures or am worried that I'm too low I'll drive 5 or 10 miles and check to see how hot the tires are. Failures from low pressure are caused by heat buildup.

I've always ran anywhere between 20 and 30 on the street and I driven around 30 miles at 4psi after snow runs and some of my friends will even pull the valve cores for a few days to get a new set of Swamper sideswalls to break in.

On new tires I alway's get the contact pattern close by slipping a credit card under the edge of the tires. I'll set the pressure so about a 1/4" of the card will slide under. Then I'll wet a spot in the driveway to drive through and check it again. On the last few sets of tires I've owned it seems like there is about a 4-6 psi range where the contact doesn't change much. I'll run the high end of that range for the most part.

There are too many variations to come up with any kind of hard number.