Tire Pressure Question
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Cross-Country
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Tire Pressure Question
This may be a dumb question, but I'm a novice when it comes to a lot of stuff on this forum. Purchased new tires from my dealer the other day; Toyo Open Country ATIII (35x12.5/R18). The tires are a D load rating, stating max pressure of 50 psi. They came back from the dealer inflated to 65 up front and 80 on the rear. This is no doubt following the recommended tire pressured indicated on the door sticker. But this sticker only applies to stock size tires right? Am I running at dangerously high pressure? My old set of Ridge Grapplers were normally run under 70 psi, but max pressure on those was 80. I know if I drop these Toyos to 50, my sensors will alert. That's not a huge deal, as I can change those settings in Forscan. But did my dealer do me a disservice by putting on a D rated tire? I tow a fair amount and occasionally haul some pretty heavy loads.
FYI, truck is a 2018 F350 6.7L.
FYI, truck is a 2018 F350 6.7L.
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From: Stephensville WI
It depends on the actual load rating of the tires, but in my opinion yes, the dealer did you a huge disservice. Some D rated tires can support a good load, so do the math before you panic.
Cargo Master
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based on Toyo's website those tires in 35 x 12.5r18 with D load rating have a max load of 2910 @ 50 psi. Thats a giving up 1060 pounds of capacity per tire vs the F rated tires. only you would know if that capacity is to low for your towing or hauling needs. but i wouldnt keep them.
Mountain Pass
Joined: Dec 2020
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My concern would be the load rating of the tire matching the weight/ load of the truck, if you never haul or pull a trailer your OK, otherwise get the 10ply-Load range E tires, they start with a LT in front of the tire size.
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This may be a dumb question, but I'm a novice when it comes to a lot of stuff on this forum. Purchased new tires from my dealer the other day; Toyo Open Country ATIII (35x12.5/R18). The tires are a D load rating, stating max pressure of 50 psi. They came back from the dealer inflated to 65 up front and 80 on the rear. This is no doubt following the recommended tire pressured indicated on the door sticker. But this sticker only applies to stock size tires right? Am I running at dangerously high pressure? My old set of Ridge Grapplers were normally run under 70 psi, but max pressure on those was 80. I know if I drop these Toyos to 50, my sensors will alert. That's not a huge deal, as I can change those settings in Forscan. But did my dealer do me a disservice by putting on a D rated tire? I tow a fair amount and occasionally haul some pretty heavy loads.
FYI, truck is a 2018 F350 6.7L.
FYI, truck is a 2018 F350 6.7L.
And, yes, I think you need a higher load rated tire if you tow heavy at all.
FTE Leadership Emeritus
Joined: Sep 2000
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From: Stephensville WI
OK, the Toyota ATIII in a 35x12.5x18 118R is rated at 2910 lbs per tire at 50PSI. The stock tires were rated at around 3815 pounds per tire, (IIRC) so you lost around 900 lbs of load carrying capacity per corner, or just potentially derated your truck by 3600 lb.
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Lead Driver
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I'm surprised that a Ford dealer not only sold you those tires, but also mounted them, and on top of that inflated them wrong. Did they have you sign something acknowledging that you know the tires are not OE spec?
Depending on your use of the truck it may be a non issue, still, they should have made it clear the differences between using that tire and using an OE spec tire.
Depending on your use of the truck it may be a non issue, still, they should have made it clear the differences between using that tire and using an OE spec tire.
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Cross-Country
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To be clear, I haven't run stock tires and rims since two months after I bought the truck. For the last 40,000 miles, I've been running a Ridge Grappler (LT295/65R20 E 129/126Q) rated 4080 @ 80 psi on 20" Fuel Podium rims with a 3700 lb rating. Had zero issues with hauling/towing. I'd have gone with the same tires, but I jumped down to an 18" rim (same lb rating as before), and he said he couldn't find any Ridge Grapplers, or any other 35" tire for that matter. He located these Toyo tires and told me they've gotten great feedback on them. I'm not opposed to the style of the tire, but I think I probably needed an E rated tire.
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Cross-Country
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I'm surprised that a Ford dealer not only sold you those tires, but also mounted them, and on top of that inflated them wrong. Did they have you sign something acknowledging that you know the tires are not OE spec?
Depending on your use of the truck it may be a non issue, still, they should have made it clear the differences between using that tire and using an OE spec tire.
Depending on your use of the truck it may be a non issue, still, they should have made it clear the differences between using that tire and using an OE spec tire.
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Cross-Country
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So if my GVWR, as stated on my door sticker, is 11500 lbs, I just need to have each tire rated at 2875 or higher, right? At 2910, I'm barely in the clear.
Someone please explain if I'm doing this wrong.
Someone please explain if I'm doing this wrong.
Lead Driver
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And, it's always desirable to have some cushion in the ratings.
Lead Driver
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And, you always have to take into account the air pressure you run, lower than rated air pressure for the tire, the lower the capacity.
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