After Alignment, tire psi 39 cold

[Rhett]

Is it normal for an Alignment shop to put more air in your tires?

 

[jimbo74]

yes, most of the time they as a general spec will put trucks @ 35

or if your alignment is not working right, they might put more air in one tire to compensate, and hope you dont notice they are differnt... by playing with the air pressure you can fake the caster adjustment

 

[Rhett]

thx for the info I wasn't sure why they did that.

I dont think they were trying to fake caster in one tire because they were all even-steven at 39 psi cold. I let them down to 32, I don't need to run 39 psi all the time.

 

[ExplorerDMB]

Depends on what your tires call for. If your running like BFG A/Ts then I put them at 40 (they call for 50psi) and go on like that. But yes, to do an alignment, all tires need to be inflated at the same pressure - or measurements will be thrown off.

-Drew

 

[Doug]

Depends on what your tires call for. If your running like BFG A/Ts then I put them at 40 (they call for 50psi) and go on like that. But yes, to do an alignment, all tires need to be inflated at the same pressure - or measurements will be thrown off.

-Drew

The pressure on the side of tire is the maximum tire pressure, do not go by that when adding air to your tires. Thier is recommended tire pressure on the door tag or I just run 30 psi in all 4 tires and I have been getting pretty even wear.

 

[CDW6212R]

I strongly disagree Doug, tires that have higher max psi listed need more air. A 44psi tire needs more air than a 32psi tire. Some newer tires, like the BFG example above, have higher psi ratings.

Tire pressure should be some tested amount lower than the max psi on a given tire. The driver tastes, and driving usage should be the other two major factors in finding the best pressure for a specific vehicle, driver, and tire.

Those door tag specs are the main reason that Ford lost those law suits. People were running those too low of air pressures, and then the slightest loss in pressure made their vehicles dangerous at high speed. When only running 28-30psi in a tire, it is extremely difficult to tell when they are really low.

If you check your tire pressures often, and keep them within 10psi of the max pressure on the tire, you will have a safer vehicle. It will get better gas mileage, and if pressure drops, you will feel it, and can see it easily.
Regards,
Don

 

[CDW6212R]

When I have an alignment done, my Pete's Alignment doesn't play with my air pressures. They may confirm that there is enough in them, but I make sure that they are where I want them before I go. I currently run about 36psi, and 34psi in my 44psi 18" tires.
Don

 

[Doug]

You're right the door tag isnt the right thing to go on with explorers. Though the number stamped on the side of the tire is the MAXIMUM PSI the tire is rated to hold. You pump 50 psi into your tire it's going to wear out the center of the tire fast. The best test for tire pressure is to do a chalk test when you buy the tires new. Or if Ford didn't put a low PSI rating on the door for better ride you could could go by the rating that came with the vehicle.

 

[CDW6212R]

My point is that the tires on most vehicles are not the original tires. A different tire needs to be treated differently from any other tire.

It is very simple to ask others who have used a tire, what pressure to use. Then start there, with a couple psi less in the rear. Very often, add or remove some pressure, until an acceptable ride is achieved. Keep the pressure as high as tolerable, below the max tire rating. Check pressures often, especially with a newly purchased vehicle.

It takes time for each person to find the best pressures for their vehicle and tires.
I tolerate higher pressures than my father. He wants to run 30 psi in his 44psi Cadillac tires. He has worn out the edges, but he does have a nice soft ride.

My 86 Crown Vic needed higher pressures to not wear out the edges. My 95 Crown Vic wore out the center of the original tires that I bought it with, using the same psi. Each tire is different, it takes time, or experience to find the best pressures.

I am sorry if I'm long winded, I'm just trying to help anyone to realize that there is no magic pressure, for a vehicle, or a tire. Good luck to all,
Don

 

[rwmorrisonjr]

Or if Ford didn't put a low PSI rating on the door for better ride you could could go by the rating that came with the vehicle.

Is that true for the 3rd Gen Explorers? If so, what pressure should I run the OEM tires at? I have them at 35 now but they seemed to get better gas mileage at 37-38 psi w/o a noticible effect on ride & handling.

 

[CDW6212R]

Find the tire rating on the actual tire, like 35psi max, or 44psi max.

Set the front tires at something around 5psi less than that rating, and the rear tires at a couple pounds less than that. Start there, and raise the pressure equally on all four until it's too harsh. Then lower the pressure equally until you have a ride which you like.

Monitor the pressure and feel the tread of the tires often, less than a month at a time.
You can play with the pressure to change ride and handling, but it will take many hundreds of miles to see any kind of tire wear pattern. This assumes that the vehicle has a good alignment.
Regards,
Don

 

[trucku]

Have a question...My 2002 xls has marked in the gas cap 30 for the fronts and 35 for the rear. should I set them both to the same pressure before an alignment? Or are they supposed to be aligned with this difference?

 

[CDW6212R]

You should have your air pressures at there normal settings. Front heavy vehicles like the Explorers should have more air in the front tires.
Don

 

[trucku]

I thought that too..but my truck specifies 30 front and 35 back.
Maybe that has to do with the speed sensor. That way the back wheel is inflated a little more and spins slower than the fronts and won't engage 4x4 all the time...just a guess.

 

[CDW6212R]

I hate to say it, but common sense needs to be used more often, in the face of "facts" from authority sources. I'd set them as I suggested. Good luck,
Don

 

[trucku]

I am sure the engineers had a good reason for the odd pressure specs. I would believe most likely to aleviate a issue that same front and rear pressure would aggittate (sp).
I also believe that since the front is more load bearing should have more pressure to compansate for tire cupping. Again..with all the trouble my 2002 xls has I still have some faith for certain guide lines given by the engineers. Unless the janitor made up the numbers...crapp.....thats a thought.

 

[gijoecam]

I work in a Ford test lab where we tested the faulty Firestones, so I've gleaned a bit of tire info.

The OEM specs in the door are for the OEM tires on a relatively stock vehicle. Those generally are set to provide an ideal compromise of ride quality, handling, and longevity.

The max pressure on the side of the tire is just that: The MAX safe cold pressure the tire manufacturer recommends for that tire and should not be exceeded for any reason. However, that pressure is also the recommended pressure for the max load on the tire. If the tire is not carrying the max load, but is inflated to the max pressure, it will cup out the center of the tread. Conversely, if the tire is at a "comfortable" pressure (i.e. one less than the max) but is fully loaded, it will wear out the edges of the tires, and generate a lot of heat internally, shortening the life of the tire.

What pressure is ideal for you? Depends.... There really is no ideal pressure as the ideal pressure for any tire varies based on the load, which varies based on the specific vehicle it's on. The pressures on the door sticker are a good starting point for most tires, but watching tire wear is the best indicator. For example, I was finding that the Michelin LTX M/S's on my Sport were cupping out the center at 40 psi, so I've dropped them to 35 psi, and the wear is much more even. On my F-150, 35 in the front feels great, but the back end is all over the place, and the rear tires cup at that pressure with an empty bed all the time, so I've been running the rears at 32 when the truck is unloaded. If I haul the boat, or any other heavy load for that matter, I fill them up to 35 to prevent squishing them.

My 2 cents on the issue....

-Joe

 

[trucku]

Thanks A bunch...great information!!! I have my truck at 32 front and back. Looks like I am getting pretty even wear So far. Although the truck wants less in front (30) i think I will go to 35 and see how the truck handles..

 

[CDW6212R]

Bingo, it's a combination of factors. People who drive hard into turns will wear out the tire edges with lower pressures,etc.
I have mentioned that my father likes a soft ride, and lower pressures. He has a 2002 Cadillac with 235/55/17's. Because of the way he drives, he isn't wearing out the edges prematurely, with lower pressures. He is running pressures in the low 30's, with 44psi max tires. He doesn't like the harder ride at higher pressures. I could not run those pressures with the way I drive. I would have to run 35+psi, and give up some of the soft ride, to achieve decent tire wear.

It's trial and error, but my best recommendation is to not err on the low side. Start with pressures closer to the max psi, and work your way down for comfort and tire wear.
Regards,
Don