Tire PSI Question

[mgmgmg]

I know this has been ask 10 million times. I have 235/75/15 Michelin AT. Ive been running 30 psi. What should it be 30 or 35 psi.


Thanks

 

[natenkiki2004]

It depends even on the year of Explorer. My 1991 says 30 PSI in the front, 35 PSI in the back. My 1994 says 26 PSI front & rear. Keep in mind that Ford only lowered tire pressure so the ride would be more comfortable. That gave us this:


If you want the most absolute proper pressure, you're supposed to fill until you think the tread is level (only works on new tires) then draw chalk on your tires tread then drive a short distance and see if the chalk is worn off evenly. Adjust from there.

Personally, I like a firm and stable ride. I believe I'm running 38 in the rear and 35 up front. Close to factory spec but firmer. Higher PSI is better in hardpack snow (less contact patch, higher pressure of the tread against the snow/ice). If you like a softer ride and don't absolutely need the best MPG or tire life, you can go lower.

 

[larrydd999]

You have a choice: 1. Look at the tire sidewall and use the pressure that the tire manufacturer recommends (and who has no idea what vehicle it will be used on). 2. Look at the driver door sticker and use the Ford (who wants to sell vehicles) recommended pressure. 3. Pick a pressure between the two that you are comfortable with.
#3 is what I go with, generally 30-32 psi on the Michelin tires I usually purchase.

 

[natenkiki2004]

You have a choice: 1. Look at the tire sidewall and use the pressure that the tire manufacturer recommends (and who has no idea what vehicle it will be used on). 2. Look at the driver door sticker and use the Ford (who wants to sell vehicles) recommended pressure. 3. Pick a pressure between the two that you are comfortable with.
#3 is what I go with, generally 30-32 psi on the Michelin tires I usually purchase.

I gotta step in here. NEVER do step 1. NEVER put your tires to the pressure listed on the sidewall. That is the absolute maximum pressure to run the tire. I made that mistake on my first set of tires and realized maybe 8,000 miles later. The ride was nice and firm but I can see now the tires are worn a little funny. Not bad and not dangerous but it's not right and you'll burn up tire life.

 

[2stroke]

Chalking your tread is the best way to find the best air pressure for the best tread wear. Its relatively easy, and my preferred method. I find about 35 psi to be about right for explorers. The maximum pressure listed on the tire is only there to tell you just that, the maximum pressure. It is usually also the pressure that the tire can carry the most weight. Explorers are well balanced, so I run 35 front and rear, but in the past I have gone up to 40 psi in the rear when towing heavy. I have since stopped this as I found no benefit. You could pick a pressure between the recommended tire pressure, and the maximum, but you would just be taking a wild guess. You would be better off just running 32 psi like average joe puts in any tire in any situation.

 

[Rhett]

I'm lazy, so I run 35 psi on my BFG's.

I have done the chalk test in the past, but I've gotten lazy nowadays. I'll chalk my new tires for sure.

 

[larrydd999]

It must have been late when I posted... You're right, Nate, that number is a maximum, not a recommendation. It seems like every time I purchase new tires the shop inflates them to a slightly different pressure (I've been using the same shop for 15+ years). I take them back for rotation at the recommended intervals and maintain their pressure between trips. They're handling any warranty claims so I go by their recommendation.

 

[2stroke]

Ask Michelin. They kinda have this tire thing figured out. Their website is filthy with optimum tire pressures.

I couldn't find any automotive tire pressure recommendations, only tractors, and other big vehicles. For auto tires, they state to use the manufactures recommendation. As we all know, 26 psi is too low, so not even the door tag is an answer to all questions.

 

[Jason94sport]

38 cold all around....

 

[shucker1]

Higher pressures make your tire balloon out and wear in the middle.
Lower pressure make them wear on the sides.

Also if you consider yourself an "Aggressive Driver" you can use different tire pressures on front and rear to correct over steer or under steer.

Caution: Be very careful when trying this. The results can be unexpected. Trust me.

 

[toypaseo]

On my Explorer, I usually run four to six PSI under the maximum PSI on the sidewall.

On the Michelin LTX M/S, and the Firestone Destination LE2 that I ran in the past, running them at the higher PSI did have slightly more wear in the middle. By the time I dismounted them and moved on to another tire, neither tire was bald in the middle by far. Sold the Michelins, and will be selling the Firestones soon, so the tread wear is the problem of the next buyer.