Tire pressure question

[RiverRatMatt]

Hey, my dad recently got a 2017 Tundra with BFG ATKO2s in 275/65R16. The dealership inflated them to 34 psi, but I seem to remember running my BFG ats at 60ish. The max is 80 psi on the tire, for a much larger truck.

What should he run his tires at? There's still snow and ice where he lives if that matters.

 

[Mudder]

Check the door jamb. It'll state what it should be front and rear.

 

[bigredmachine]

if their load range e run at about 60 or so, that's what I do with mine. if their not lt tires id set them at 40

 

[RiverRatMatt]

Check the door jamb. It'll state what it should be front and rear.

Isn't that only relevant for the stock tires?

 

[Mudder]

If the size hasn't changed I think it would still work. The real way to figure this out would be to check the tread pattern with calk and a clean spot on the ground. Inflating/Deflating until the contact patch is the same width as the tread pattern.

 

[PADDO]

Hey, my dad recently got a 2017 Tundra with BFG ATKO2s in 275/65R16. The dealership inflated them to 34 psi, but I seem to remember running my BFG ats at 60ish. The max is 80 psi on the tire, for a much larger truck.

What should he run his tires at? There's still snow and ice where he lives if that matters.

Down load a copy of "Tire Load/Inflation tables" and set pressures accordingly. These tables will also help you convert from the OE stock spec to a different P metric or LT tire where necessary. No need to guess or over/under inflate.

 

[Hilux safari]

On my 105 I have 265/75/16 BFG A/T KO2. I run them at 40-45 Psi or about 3 Bar. I get a much more comfortable ride, although our roads have plenty of potholes.

 

[Greenbean]

Down load a copy of "Tire Load/Inflation tables" and set pressures accordingly. These tables will also help you convert from the OE stock spec to a different P metric or LT tire where necessary. No need to guess or over/under inflate.

Link?

I found Toyos info online and asked the Help Desk at BF Goodrich about my 275/70R16 KOs and they just replied 55 psi, which I don't believe on a stock 2000 LC...

Anyone have inflation tables for BF Goodrich tires? KO2 or KO?

 

[PADDO]

Link?

I found Toyos info online and asked the Help Desk at BF Goodrich about my 275/70R16 KOs and they just replied 55 psi, which I don't believe on a stock 2000 LC...

Anyone have inflation tables for BF Goodrich tires? KO2 or KO?

Use the tables published by Toyo as the data is derived from the US Tire and Rim Association and Rubber Manufactures Association standards. These standards aren't manufacturer specific, just ensure you follow the P to LT conversion derating process and select a pressure that equals or exceeds the OE tire placards pressure specs for GVWR and GAWR. On the face of it, for a 100 series fitted with LTs, you're looking in the 35-40psi range to match specs, probably 38psi if not towing or heavily loaded.

 

[Greenbean]

Oops, I need to do my derating calculations...

Thanks bud.

They will be set right today!

 

[Greenbean]

OK so according to the tables the standard P275/70/R16 has these specs...
Front at 29-psi equates to 2359 divided by the 1.1 reduction factor gets me at 2145
Rear at 32-psi equates to 2480 divided by the 1.1 reduction factor gets me at 2255


When I look at the LT of the same size I see
Front needs to be at 41=psi to be at 2145
Rear needs to be at 44=psi to be at 2260

Obviously as I add weight I'll adjust up.


Both these are with no loads as Toyota specked out in the door jam sticker.
Basically I reverse calculated from the stock Ptire as to what weight load the
LC was looking at and then cross referenced that with the LT table.

Am I looking at all this correctly?

 

[PADDO]

OK so according to the tables the standard P275/70/R16 has these specs...
Front at 29-psi equates to 2359 divided by the 1.1 reduction factor gets me at 2145
Rear at 32-psi equates to 2480 divided by the 1.1 reduction factor gets me at 2255


When I look at the LT of the same size I see
Front needs to be at 41=psi to be at 2145
Rear needs to be at 44=psi to be at 2260

Obviously as I add weight I'll adjust up.


Both these are with no loads as Toyota specked out in the door jam sticker.
Basically I reverse calculated from the stock Ptire as to what weight load the
LC was looking at and then cross referenced that with the LT table.

Am I looking at all this correctly?

I think you'll find that the tire placards 29/32 psi has taken into account recommended maximum cargo and passenger weight already (add 3psi front and rear for towing). Courtesy of @whitenoise here are the measured corner weights of a stock 03 LX, full tank, sans 3rd row: LF 1488 lb, RF 1391 lb, LR 1334 lb and RR 1320 lbs for a total of 5533 lbs and 52/48% distribution. So, a P rated 275/75R16 @29 psi is good for 2145 lbs (derated) which gives about 650 lbs extra capacity over each unloaded measured front corner weight and the rears @ 32 psi gives you 2255 lbs (derated) which gives you an additional capacity of about 920 lbs for each rear corner. Seems to me that if you don't exceed the designed weight limit (1200 lbs for cargo + passengers) and run recommended pressures as per the tire and rim association that match the OE tire specs then you should be good to go. FWIW I run 36 psi F/R in LT 275/75R18s, Discount tires installation receipt recommended 35psi, the guys that fitted them inflated to 40 psi.

 

[Greenbean]

That's good to know, thanks.

I didn't realize that the 29 and 32 was for a fully loaded rig. Makes sense to me now after the fact, lol...

I'll recalculate tomorrow and drop them a few PSI for sure.

Appreciate your time and attention in helping me figure this out. It's all is rather interesting.

Discount tire set all mine at 35 and I thought it might be a tad low but before diving into these equations and all, I had returned from about an hours worth of driving and decided to check the pressure and each tire was at 37 psi. So I knew they were ok as that's a safe increase but I decided to dig and educate myself a bit to be wiser I hope.

 

[abuck99]

275/70-18 BFGK02 on stock rims. I run 32-35 psi all around. I've tried higher pressures to improve econ to no avail, and it diminished ride quality.

 

[mmajsw]

I use the chalk test as each vehicle is loaded differently with different tire sizes. The manufacturer pressures are a good starting point but the chalk test allows me to run the optimal pressures for my tire and vehicle combination.

Instructions

1. Fill the tires to a good starting pressure. If you are unsure what pressure to start with then subtract 10 percent from the manufacturer's maximum inflation pressure on the side of the tire. If, for example, the maximum is 40 psi, then 10 percent of 40 is 4. Subtract the 10 percent value from the maximum psi value. So, 40 - 4 = 36. Use 36 psi in your tires. You could also use the following calculation for the starting pressure.
   • Weight of vehicle / (Manufacturers weight rating x 4)) x Manufacturers inflation pressure at weight rating
2. Drive to a flat area. This can be your driveway or the street in front of your house. Just make sure there aren't a lot of cracks, bumps or pot holes in the ground.
3. Using chalk, draw a thick, straight line across the width of the tire.
4. Use Test Variance 1 or Test Variance 2 for the completion of the instructions.

Test Variance 1

1. Drive the truck forward at least one-full truck length.
2. Inspect the chalk on the ground. A tire with the proper air pressure should press the chalk line evenly across the ground. This means you'll see the entire chalk line imprinted on the ground. If your tire is over-inflated, you'll only see a small portion of line in the center. If you're tire is underinflated, you'll see only the sides of the lines since the middle of the tire is not making contact with the ground.
3. Adjust your tire's air pressure according to the chalk test results and try again until you get the chalk line to press evenly across the ground.

Test Variance 2

1. Drive the truck to the end of the street and back or around the block.
2. Inspect the chalk on the tire. A tire with the proper air pressure will show the chalk evenly worn across the tire. If your tire is over-inflated, the center of the line will be worn more than the edges. If you're tire is underinflated, the outer edges of the line will be worn more than the center.
3. Adjust your tire's air pressure according to the chalk test results and try again until you get the chalk line to evenly wear across the tire.

Over-Inflated = More wear on the center of the tire = center of chalk line visible on ground = chalk line worn more in center

Under-Inflated = More wear on the outer edges of the tire = outer edges of chalk line visible on ground = chalk line worn more on outer edges

 

[LandCruiserPhil]

More info on proper tire inflation of large tires than you ever wanted to know.

 

[calskibum]

Hmmm...I thought I had the tire pressure thing figured out, but after reading this thread, I'm not so sure so any advise is welcome. I have a '99 LC and I just changed the tires from the LTX P275/70/16 to the KO2 of the same size. The door placard indicates 32 psi front and rear for the P275/70/16 size. On the new KO2s, I set the cold psi to 45 and the chalk test looked good and even. Driving a family of 4 on the freeway for 20 miles showed a pressure increase of 5 to 6 psi, which based on some other threads on mud that seems to be good for the LT tires. My LC is pretty stock without added weight. It's mostly hauling a family of 4 plus whatever we bring for camping trips and etc.

Based on reading this thread, it sounds like I may be setting my pressure on the high end. At 45 psi, it's riding a bit firmer than my preference, but that may be because I just switched over from the LTX and not yet used to the LT tires. However, if lowering it to 40 psi doesn't run any safety risks or significantly reduce the mpg, then I'm all for it.

Thoughts?