What PSI For 275/55R20 Tires?

[Frasher4Runner]

Got new tires put on yesterday and realized I don’t know what pressure to run them at. Went up from the factory size to 275/55R20, which is common. I believe factory spec is 32 PSI but what should these be? Still 32 or something else? I checked all 4 and they’re at 42 right now from the tire shop.


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[fkheath]

42 is way to high. Keep them at 32. With slightly larger tires, you can run a bit lower.

Just be sure you use a good/accurate tire gauge. The stick kind is junk.

 

[Tuco S.]

If your new tires are also P-metric SL loads, they should also be 32 psi.

Tire Pressure Calculator

 

[Frasher4Runner]

If your new tires are also P-metric SL loads, they should also be 32 psi.

Tire Pressure Calculator

That calculates out to 27 PSI. Is that really correct?!


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[patkelly4370]

10% rise in psi from cold to warmed up.
(random starting number) Cold tire 30psi. Warm ideally would be 33psi. If warm is too high (35 or morel, increase cold psi. Under inflated warms more.
If warm psi is less than 10% then cold psi too high. Tire doesn't warm up enough to develop traction.
This is all dependant upon ambient temperature, load, type of driving, etc. Monitor daily for a week or so and find your average.
I learned to do this road racing motorcycles (track, not public streets).
So for MY tires where I live, I run 30psi in winter (temps down to the 20°`s) and 37psi in summer (up to 120°+).

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[lewis26]

Do the Chalk test.

Using The Chalk Method for Determining PSI | Interco Tire

 

[Frasher4Runner]

If your new tires are also P-metric SL loads, they should also be 32 psi.

Tire Pressure Calculator

Based on this, I reduced the PSI to 30 before I drove to work this morning. On the drive in, the truck was pulling to the left and I had a small bit of wobble/shake in the steering wheel. Prior to letting the air out, when at 42 PSI as from the tire shop, no pulling or wobble, just a smooth ride.


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[Jivewalker]

Did you change from "P" to "LT"? What was your factory tire?

 

[Frasher4Runner]

Did you change from "P" to "LT"? What was your factory tire?

I’m not sure what it said on the old tire itself but I believe they were still factory tires. The door jamb sticker says P245/60R20. What I have now is 275/55R20, no P or LT.


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[meltdown]

I’m not sure what it said on the old tire itself but I believe they were still factory tires. The door jamb sticker says P245/60R20. What I have now is 275/55R20, no P or LT.


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I think what he’s getting at is your psi should be based on the load index of the tire, not the size. A P rated tire and an E rated tire of the same size would have different recommended pressures.

 

[Frasher4Runner]

I think what he’s getting at is your psi should be based on the load index of the tire, not the size. A P rated tire and an E rated tire of the same size would have different recommended pressures.

That’s fine and dandy but I need to figure out what that pressure is! LOL


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[Tuco S.]

Post the manufacturer link to your new tire. The specs will show the load rating. Enter the load rating in the tire pressure calculator, and it will kick out a psi.

 

[Jivewalker]

What everyone is saying is correct. You need to find out if your new tire is "P" or "LT", then you can figure out what pressure you should run based on the weight of your vehicle, or, in this case, the weight rating of your stock "P" tires. You will cross reference that to a similar or greater weight rating to your new tire and that will tell you the pressure. The calculator posted above makes it easy if you know the correct tire info.

For instance, my stock P tires were at 32 psi. I went to an LT in the same exact size and I run them at 44psi.

 

[Tuco S.]

The tire pressure calculator shows 3 different options for that tire size:

Metric 27 psi (SL or XL load)
P Metric 26 psi (SL load)
LT Metric 37 psi (D or E load)

 

[Frasher4Runner]

Post the manufacturer link to your new tire. The specs will show the load rating. Enter the load rating in the tire pressure calculator, and it will kick out a psi.

COOPER DISCOVERER® AT3 4S™

 

[meltdown]

27 psi.

Assuming the stock tires were SL (107 load index) at 32 psi they will carry 1940 lbs. Your new tire is XL (117 load index). At 27 psi, it can carry 1987 lbs.

Those weights actually seem low for the 4Runner though. I was thinking they should be around 2200 - 2300lbs.

Im running 33 psi on my XL tires, but they are 116 load index. Still dialing them in as well.

 

[Tuco S.]

Yep, your tires are the XL load so try 27 psi. That should get you in the ballpark. You can always fine tune later on with a chalk test.

Lots of tire shops over-inflate them when new as it supposedly helps the tires to seat. I always check psi on every tire right after I leave the tire shop because pressures can be all over the place.

If your car is pulling to one side at 27 psi, you might want to get an alignment check.

 

[Frasher4Runner]

27 psi.

Assuming the stock tires were SL (107 load index) at 32 psi they will carry 1940 lbs. Your new tire is XL (117 load index). At 27 psi, it can carry 1987 lbs.

Those weights actually seem low for the 4Runner though. I was thinking they should be around 2200 - 2300lbs.

Im running 33 psi on my XL tires, but they are 116 load index. Still dialing them in as well.

That’s what I was coming out with as well. I guess I’ll air down and see how it goes.


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[NYRunner]

Am I crazy for preferring to keep my 20” Yokohama’s inflated to 35/36psi? My truck feels much nimbler that way than at 32...

 

[Frasher4Runner]

I decided to call Cooper Tires and ask them what PSI they recommended for my new tires. I gave the lady my vehicle info, old tire size, PSI recommendation on the vehicle and the new tire size. She looked it up and said her book said 26 PSI (so I guess the 27 that the one website was spitting out for me was accurate) but recommended I run 30-32 to keep the low tire pressure light from coming on.