Tire pressure for 285s

[brad152]

When I picked up my ORP with BFG K03 285/70R 18 the dealer had the tire pressures set to 51 lbs, seems pretty high to me, any reason they would do this?

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[SunnyOffroad]

No idea. Mine was about 45 psi from the dealer pickup. Felt like driving a tank until I dropped them to 33 psi.

 

[Gumpus]

Tire pressure set high at factory to minimize flat spotting during shipment and storage. I bet your dealer didn't even check because that aint the right pressure.

 

[morsk]

Mine was around 45. Dropped it to 33 the second I pulled into my driveway.

 

[brad152]

Tire pressure set high at factory to minimize flat spotting during shipment and storage. I bet your dealer didn't even check because that aint the right pressure.

That makes sense, thanks

 

[RunnerRocks]

During very rough stiff test drives, I suspected dealers had not set tires to the proper PSI. When I asked them where to check PSI on the dash, they couldn't find it.

 

[828findadventure]

Here is my experience with 18" 275/70/18 AT tires that were E-rated on my Tundra. I had numerous balance issues and steering wobble at the manufacturer's door-jam cold PSI. After many trips to the dealer, a tech put 42psi in each cold. That fixed the issue for me; no more wobble. Now, if you're running KO2s, they have issues on their own, but if the E-rated tire is road force balanced, you should be good. Note: tires expand with heat, and my PSI would go up to around 50 PSI after long, hot summer drives. Hope this information helps, and maybe explains why the tech seemed to overinflate the tires.

 

[MikeD]

When I picked up my ORP with BFG K03 285/70R 18 the dealer had the tire pressures set to 51 lbs, seems pretty high to me, any reason they would do this?

Hmm... This implies that you had the dealer put on the larger tires (stock is 265/70R18). Which means the dealer actually put the air that high.... which seems odd. It is NOT odd for the vehicle to come off the truck with very high pressure for reasons repeated in this thread and MANY places on the forum. Mine were at 55 PSI - dropping to spec 33 helped the ride a ton.

Personally, I use this guide to choose pressure for my 285/75s: Tire Pressure calculator. It gives me 36 PSI. And it gives 42 PSI for the 275/70R18 E-loads described above. - consistent with what was done.
For your BFGs the calculator returns 39 psi for both C and E load. Much lower that how they were set but still higher than stock 265/70 SLs.

 

[ThatSickRIp]

Hmm... This implies that you had the dealer put on the larger tires (stock is 265/70R18). Which means the dealer actually put the air that high.... which seems odd. It is NOT odd for the vehicle to come off the truck with very high pressure for reasons repeated in this thread and MANY places on the forum. Mine were at 55 PSI - dropping to spec 33 helped the ride a ton.

Personally, I use this guide to choose pressure for my 285/75s: Tire Pressure calculator. It gives me 36 PSI. And it gives 42 PSI for the 275/70R18 E-loads described above. - consistent with what was done.
For your BFGs the calculator returns 39 psi for both C and E load. Much lower that how they were set but still higher than stock 265/70 SLs.

Interesting. I just used it to see what it says for mine since I just put on Cooper Discoverer AT3 4S 285/70 17s and its saying 26 PSI...

 

[MikeD]

Interesting. I just used it to see what it says for mine since I just put on Cooper Discoverer AT3 4S 285/70 17s and its saying 26 PSI...

Having used the tool a bunch I was surprised by this result - and even though I got a different answer, it is still a bit surprising to me: 28 PSI (and see the note: "may be too low for optimum tread wear"). But I guess that those 285/70R17 just have more load carrying capacity.

Note that the same size tire in LT (LT285/70R17) wants 40 PSI (whether C, D, or E-load). Somewhat counter-intuitive to me that the heavier duty tire needs higher PSI. But I obviously don't understand all the factors in play.

Note that I used the off-road trim standard 265/70R18 in SL at 33 PSI as comparison point in image above. When I switch that to the SR5 standard 265/70R17 and same 33# PSI.... There is your 26 # answer. Surprising to me that going from 265 to 285 makes such a big difference in load capacity - I guess there is just a lot more rubber in the 285/70.
Assume you are running those P285/70 SLs at 32-33 PSI?

 

[ThatSickRIp]

Having used the tool a bunch I was surprised by this result - and even though I got a different answer, it is still a bit surprising to me: 28 PSI (and see the note: "may be too low for optimum tread wear"). But I guess that those 285/70R17 just have more load carrying capacity.

Note that the same size tire in LT (LT285/70R17) wants 40 PSI (whether C, D, or E-load). Somewhat counter-intuitive to me that the heavier duty tire needs higher PSI. But I obviously don't understand all the factors in play.

Note that I used the off-road trim standard 265/70R18 in SL at 33 PSI as comparison point in image above. When I switch that to the SR5 standard 265/70R17 and same 33# PSI.... There is your 26 # answer. Surprising to me that going from 265 to 285 makes such a big difference in load capacity - I guess there is just a lot more rubber in the 285/70.
Assume you are running those P285/70 SLs at 32-33 PSI?

Interesting info
SR5 standard were 245/70 R17 and thats what I used for the calculator.
They were just put on Saturday and were at 35-36. I need to drop them to 33 still

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