BFG AT KO2 tire PSI

[JMyerz]

Got a new set of 265/70R17 BFG AT KO2 C rated tires. They are on my 2014 Ram 1500 Crew cab outfitted with a canopy, custom deck/bed, and a 50lb rack, I figure about 300lbs in the rear of the truck with this setup. Discount tire inflated them to 35psi which obviously drives like marshmallows, so I filled them to stock "p rated" tire psi of 42 but I still don't think its right. Is there a conversion of going from a p rated to c rated tire for psi? I kept the tire size the same.

I would do the old school chalk test on the tread but it's been raining pretty good here so that's out.

Thanks!

J

 

[Tazman]

Take into consideration the weight you are carrying. I have a KO, not sure of the weight rating, nut I keep mine under 40 lbs, unless I have my trailer attached, then I bump them up to 45. I don't vary the front from -40lbs. Thus far, this seems to work for me. My truck is a GMC 1500 4x. You will LOVE that tire.

 

[coop74]

Michelin has a chart on their webpage that shows the recommended tire pressures based on weight for their tires. That is a good place to start and then look at the increase of pressure from cold temps to hot pressures. Ideally you will get 10% increase in pressure when you hit the right tire pressure.

http://www.michelinrvtires.com/reference-materials/load-and-inflation-tables/#/

The link shown is RV pressures, dig around to find their all terrain tires...

 

[verdesardog]

Get your front and rear axles weighed then use the correct load/inflation table for your tires to find the correct pressure for what the tires are actually carrying..

 

[CSG]

I've discussed this a couple times before but few people seem to pay attention. I'll post this link one more time to help you determine the proper tire pressure for your tires. When you move from the P rated tires that likely came on your truck, you have to do some math to get the equivalent pressure in LT tires. Read through the following tables carefully and don't forget to look at how P tires are rated for load on SUVs and light trucks.

https://toyotires-1524598101.netdna...ication_of_load_inflation_tables_20151020.pdf

 

[Regcabguy]

It amazes me that manufacturers continue to outfit 1/2 ton full size trucks with P-rated tires.
I met a Canadian guy towing his 22' trailer with a Tundra. Liked the power,braking but hated the fuel economy and especially the handling. To Toyota's credit the truck had Bilstein shocks but again passenger tires. I advised him to hit Les Schwab and put some E-rated ones on. He had the anti sway bars also. Everything but some decent tires.

 

[eggman918]

With my Cooper's i weighed the axles and E-mailed them with axle weight, tire style,size and rim width and they got back to me within 24 hours...$.02

 

[JMyerz]

This is exactly what I was looking for, thanks! I knew there had to be a mathematical equation to this.

I've discussed this a couple times before but few people seem to pay attention. I'll post this link one more time to help you determine the proper tire pressure for your tires. When you move from the P rated tires that likely came on your truck, you have to do some math to get the equivalent pressure in LT tires. Read through the following tables carefully and don't forget to look at how P tires are rated for load on SUVs and light trucks.

https://toyotires-1524598101.netdna...ication_of_load_inflation_tables_20151020.pdf

 

[JMyerz]

Agreed! To make matters even worse the OEM recommended PSI on the prior P Rated tires exceeds the rating on the manufacturers load tables

It amazes me that manufacturers continue to outfit 1/2 ton full size trucks with P-rated tires.
I met a Canadian guy towing his 22' trailer with a Tundra. Liked the power,braking but hated the fuel economy and especially the handling. To Toyota's credit the truck had Bilstein shocks but again passenger tires. I advised him to hit Les Schwab and put some E-rated ones on. He had the anti sway bars also. Everything but some decent tires.

 

[proper4wd]

P-rated does not necessarily mean low load rated. It's entirely possible that the C-rated tires you put on have a lower load rating than the "P" tires that came off.

Example, any 115 rated tire (for which there are many in that size) has a stated capacity of 2679 lbs.

113 rated tires (the balance of those that aren't 115 in that size) are stated at 2540 lbs capacity.

The C-rated BFG KO2 has a stated capacity of 2470 lbs.

 

[Webfoot]

I see you already have new tires so my post in your other thread is a bit late.

Regarding load tables don't forget to de-rate non-LT tires by a factor of 1.1 when used on a truck, i.e. divide the stated load capacity by 1.1. Also don't confuse P-Metric and ISO Metric as they are two different standards. I see a lot of people calling any non-LT tire "P" even when it is not.