Interesting find on tire pressure

[ThatSickRIp]

So, there was a post here a while back that had an online calculator for setting your tire pressure for the tires size and load rating. It recommended 27 PSI for my 285 70 17. I have them at about 32.

Just now I was looking at my receipts folder for the 4R, and I noticed the tire installer receipt list 26 PSI as recommended pressure, so very close to the online calculator above.

Has anyone gone this low on their tire pressure, and if so how were the results?

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[josiahg52]

The required tire pressure is determined by the size and expected load per the Tire Load and Inflation Tables published by the TRA. Or you can just use what the door sticker says. Instead of running 80 psi in the rear tires on my Ram 2500, I found that there is really no need for more than 60 psi, IIRC, based on the rear axle and payload rating. I reprogrammed the TPMS set points to 60psi front and 40psi rear. If the weight of your vehicle and tire size supports it, 26 or 27psi wouldn't phase me as long as it falls within the tire manufacturer's pressure range.

 

[Dr_Al]

Back in the day radial tires were suppose to be at 28 psi. Bias tires needed to be at 32 psi. Then the whole Firestone Ford Explorer thing happened. Lots of fingers got pointed and suddenly they changed it to 32 psi. Fuel economy improved and suddenly 28 psi went away. There was some nonsense about other reasons (vehicles being heavier) but in the end nobody wanted to take the blame for a tire failure because it got too hot from running at a low pressure.

The real reason for the Firestone problem was a manufacturing problem. I think it was compounded by tires that were unusually old for a new tire. Ford made it worse by recommending 26 psi to improve the ride. I always set my tire pressure after the garage swaps the summer/winter tires. I've seen them as high as 38 psi (which will wear the center of the tire quicker than the edges). I usually set them to around 30 psi. If I was to go lower I would check them after about 5k miles to make sure the edges aren't wearing faster than the center.

If I was going on a trip pulling a trailer or loaded down I would air them up to at least 32 to handle the extra weight. But for normal use 27 psi wouldn't bother me.

 

[ThatSickRIp]

Thanks fellas

I think Ill give it a shot and see how it rides. When we load up for trips/vacations, I can always put a few PSI in to be safe, though we never pull a trailer so should still be good to go.

 

[morsk]

Sorta tangential, but I was looking at my stock 245/70/17 Yokohamas yesterday inflated to ~33 and they looked kinda flat. Rides well though, but was wondering if I should pump them up to 36

 

[bakutheleo]

I have seen that "kinda flat" look on quite a few vehicles, including others I have had (so I know the pressure was to spec). My guess is that going by looks is not a good idea--just go by the recommended pressure and it should be good.

 

[Skrr1225]

So, there was a post here a while back that had an online calculator for setting your tire pressure for the tires size and load rating. It recommended 27 PSI for my 285 70 17. I have them at about 32.

Just now I was looking at my receipts folder for the 4R, and I noticed the tire installer receipt list 26 PSI as recommended pressure, so very close to the online calculator above.

Has anyone gone this low on their tire pressure, and if so how were the results?

If your 285s are SL tires, online load calculators commonly output roughly 26–27 PSI to match the original factory load capability. Running them at 32 PSI may feel noticeably stiffer or slightly over-inflated for daily pavement use.

 

[ThatSickRIp]

If your 285s are SL tires, online load calculators commonly output roughly 26–27 PSI to match the original factory load capability. Running them at 32 PSI may feel noticeably stiffer or slightly over-inflated for daily pavement use.

I think I'll drop to 28 and see how it feels and go from there.

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