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-   -   Wheel Pressure Rating? (http://www.tacomaworld.com/forum/wheels-tires/273141-wheel-pressure-rating.html)

mkillora 04-14-2013 08:56 AM

Wheel Pressure Rating?
 
Could someone please tell me what the wheel pressure rating would be for a 16 X7JJ wheel? I have them on my 2011 Tacoma and just went with Goodyear Wrangler LT 265/70R/16 tires. Dealer recommends that I go to 70 psi on the tires, but somewhere I saw that the J on the wheel indicates that the max psi for the wheels is 65(?). Haven't been able to find anywhere, reliable information on this.

thanks

MadToy 04-14-2013 11:08 AM

70 psi? Dealer on crack?

DevL 04-14-2013 11:12 AM

WTF? Start around 30. Do a chalk test. Run 15-20 offroad. Why in God's name would you run 40, 50, or 60psi?

mkillora 04-14-2013 12:08 PM

Just for further clarification, these are LT tires with and E rating. The sidewall indicates 80 psi at max. load.

MadToy 04-14-2013 12:19 PM

Quote:

Originally Posted by mkillora (Post 6740477)
Just for further clarification, these are LT tires with and E rating. The sidewall indicates 80 psi at max. load.

Should be around 38-40 psi. Max load would be what you fill it to on a 1 ton truck with full payload....

DevL 04-14-2013 09:40 PM

Again... WTF? I run E rated tires... 30 psi because its proper for my vehicle's weight. Are you hauling lead pipes filled with uranium? No way you should be running 38-40 psi in a Tacoma.

Air in tires is a spring. Any spring should be just stiff enough for your load. Once your tread wear is even more air pressure is only negative.

MadToy 04-15-2013 06:41 AM

Quote:

Originally Posted by DevL (Post 6742749)
Again... WTF? I run E rated tires... 30 psi because its proper for my vehicle's weight. Are you hauling lead pipes filled with uranium? No way you should be running 38-40 psi in a Tacoma.

Air in tires is a spring. Any spring should be just stiff enough for your load. Once your tread wear is even more air pressure is only negative.

An LT tire will require more PSI than a P rated tire of the same size. So if the P tire takes 30 psi (door jamb), then the LT tire will be more. Maybe not 38-40 unless the tire is smaller, but definitely more than 30. Example - an LT 255/85/16 (33") needs right around 40-42 PSI to match the same load rating as the P265 stockers, and chalks perfectly on the Tacoma.

The tire inflation chart is nearly always spot on - so that's where you should start, then chalk from there.

mkillora 04-15-2013 07:21 AM

Thanks very much for the feedback/info, to date. Also, I'm regularly pulling a 2 ton travel trailer with the truck. One of the reasons the dealer suggested the LT's over the stock P's.

DevL 04-19-2013 07:22 PM

Quote:

Originally Posted by MadToy (Post 6743668)
An LT tire will require more PSI than a P rated tire of the same size. So if the P tire takes 30 psi (door jamb), then the LT tire will be more. Maybe not 38-40 unless the tire is smaller, but definitely more than 30. Example - an LT 255/85/16 (33") needs right around 40-42 PSI to match the same load rating as the P265 stockers, and chalks perfectly on the Tacoma.

The tire inflation chart is nearly always spot on - so that's where you should start, then chalk from there.

No, that is due to the tire being narrower, not LT. LT tires do not REQUIRE more air, but can accept more air.

MadToy 04-19-2013 07:54 PM

Quote:

Originally Posted by DevL (Post 6768879)
No, that is due to the tire being narrower, not LT. LT tires do not REQUIRE more air, but can accept more air.

Don't want to argue, but you're absolutely wrong, and would rather not have folks be misinformed by your statement.

Since I prefer to back my statement up with facts, here's a load inflation chart from Toyo Tires. You can read it all for good info, or just go to page 11 (95 on the document) and read the red warning message.

http://cache.toyotires.com/sites/def...ationTable.pdf

DevL 04-20-2013 10:57 AM

You are misunderstanding what you are reading. P rated tires DO NOT USE THE SAME FORMULA for generating the LEGAL load rating. You are discussing the LEGAL rating and NOT the actual capability to handle a load. LT tires have a reserve of over pressure for their legal "rating" vs P rated tires which do not... but that in no way shape, form, or fashion makes the LT rated tires able to handle the load less than a P rated. Its just a legal difference. To get similar load ratings you must multiply the P rated tire by .9 to get an equivalence.

A tire with a P rating that can handle X pounds is slightly less capable of handling the load as an LT tire rated at 5% less of a load. The P rated tire is less capable at the same pressure as the LT rated tire. See... you do learn something new every day dont you. ;)

To reitterate: LT tires, like commercial motor vehicle tires, are required to have additional pressure, purely as a precaution, and mandated by law. Just becasue P rated tires are not required to have the same extra presure as an extra layer of protection for over loading, does not mean they require less pressure to handle an actual load. A taller, narrower tire will require a higher pressure becasue of its dimensions.

Our trucks have lower pressure in front than rear. This is due to the rated loading for the bed when loaded... it does not make it the right pressure for use with nothing in the bed... again legal vs real.

MadToy 04-20-2013 05:18 PM

OP, start at 40 psi and chalk from there. You'll be within 2-3 psi of where you need to be. This is assuming your original tire size was the same in P Metric. I would stick closely to the load chart since you tow a heavy trailer regularly. You absolutely do not want to under inflate your tires when towing (legally or not)

P265/70r17 - 29 psi = 2315 load capacity. Light truck capacity is 2104 (2315/1.1)
LT265/70r17 - 40 psi = 2075 lbs capacity.

This is what Toyo Tires recommends (doesn't really matter which manufacturer), not a random guy on the Internet. :frusty: You can also email the manufacturer of the tire you're getting and ask them.

I have learned something by the way, but nothing new. Same lesson I learned when trying to argue with my kids. They're always right :D

DevL 04-22-2013 12:57 AM

You mad bro? LOL

Stronger tires with extra rubber, extra plies, etc. DO NOT physically need more air pressure to handle a given load of weight. What physics did you think was at work to make such an assertion? You just have to open your mind and think rationally for a moment. An unloaded and stock:4x4 V6 crew cab Tacoma has ZERO use for ANY tire pressure over 29 pounds front or rear regardless of tire design. For greater loads use more air till you get flat tread with that load. There is no formula or manufacturer recommendation that can improve on such a simple and logical concept. Legal constraints and manufacturer ratings are about lawsuits, not what is best. Or do you leave your truck unmodified as is recommended by the manufacturer. 40 lbs is WAY too high as a place to start for any Tacoma.

Don't take my word for it... try it for yourself. Your 40-70 pound tires will feel like Fred Flintstones.

MadToy 04-22-2013 07:07 AM

Mad? Yes- it's in my screen name :D

I don't mind a good debate. I'm not making any assertion at all. I'm simply directing you to the actual manufacturers articles that contradict your opinion. If you reference some industry standard articles to back up your statements, I would give your opinion more merit. I'll keep an open mind. As long as your proof isn't another TW thread with someone else's opinion :cool:

To add some proof to my argument, here are a couple more links to Nitto and Yokohama articles. If you can prove your point with some facts, I'll gladly send Toyo, Nitto, and Yokohama a note letting them know they're all wrong :o:

Nitto

Yokohama

mkillora 04-23-2013 08:32 AM

Well, gentlemen, this has turned into an interesting debate. As we're currently on a road trip to Florida and have already covered 17,000 miles, my "experiment" with these LT tires continued. So far, here's the history:

-started trip with tires at 50 psi. based on tire dealer's recommendation;
-bumped them up to 70 based on recommendation from Goodyear due to the handling problems that I was having;
-as the higher psi. was not helping, I've now gone in the totally different direction, - down to 45 psi on the rears and 42psi on the fronts. Won't be able to test this with the trailer hooked up as we're stationary at our present location until next Monday, (April 29th). Then we will be heading north to Canada and we'll see if reducing the pressures is going in the right direction.
I have a friend who is a technical engineer at a Good year plant and he advises not to lower the pressure in these tires past 42 psi. In his words they like the higher pressures. Although he has not come right out and said it, I get the impression that these tires are overkill for the Tacoma and the weight that I am pulling.
I'll keep you informed on how things progress.
Thanks again for all of your input.

mkillora 04-23-2013 08:38 AM

Just a small correction to my previous post. My technical friend at Goodyear, recommended not going down further than 35 psi on these tires, i.e. LT 265/70R/16's.

Thanks again!

bldegle2 04-23-2013 08:44 AM

29 front, 32 rear for most 2nd gen, heavier truck

26 front, 29 back for most 1st gen, lighter truck

the 26/29 is right from Prerunner TRD door jam, and the 29/32 I got when cruising the new 2nd gen models one day on the lot while looking at the OEM 17" alloy wheels and measuring Backspacing from underneath...

Certainly you can run more, you will get better MPG for sure, just a little rougher ride...

I run mine 27/27 with no load, crank the rear to 30+ depending on load...get very even wear with regular rotations...

YMMV

DevL 04-25-2013 05:38 AM

For any given tire there is ONE tire pressure that is ideal for a given weight on that tire. As you get closer to that weight the tread will flatten out instead of riding on the outside edges and you will be less likely to hydroplane and increase milage, decrease tire tread temperature, etc. As you go over that weight the tire will bow and ride more on the center of the tread. If you can determine this ideal air pressure for your rig, use that. The manufacturers probably know this air pressure. They would still give you 10% greater air pressure than that figure because they are required to by law because they put an LT designation on that tire, not for any other reason. IT IS MANDATED. You actually lose things going over the one and only ideal pressure. Traction in the wet and ride quality are two of them. The manufacturer may NOT tell you to run the propper tire pressure in an LT tire. They MUST allow a 10% over pressure safety margin. This will absoloutely increase the odds of hydroplaning. The wet traction does not level off, it will increase to the best pressure point then drop at higher pressures. These are all well known and well established occurances not only in car and light truck tires but all other tires as well including commercial, military, and aircraft tires. ONE pressure gives the best traction and performance.

Polymerhead 04-25-2013 05:44 AM

27 lbs in my Hankooks would be ridiculous. I'd crack a sidewall PDQ. I run 38 in mine, with a sidewall max rating of 44. Nice flat contact patch and smooth ride. The pressure rating on the door jamb goes right out the window the second you change tires.

mkillora 05-26-2013 10:40 AM

Well gentlemen, the road trip is over and we returned home last week. The LT tires continued to be problematic and I tried psi's ranging from 40 to 70 during the trip. Nothing worked and I drove on ice for the total of about 4500 miles that we put on. The best handling I could get out of these LT's was the fronts set at 60 psi and the rears at 65. But believe me, this was not a solution to the handling problems.
The dealer where I purchased the LT's has now swaped them back to a P rated tire and installed Michelins MSX. Although I wont be taking another road trip until this fall, I'm confident that the P rated tires will perform just fine as did the original equipment BFG's.
Moral of the story is that the LT's were way toooo much tire for the Taco.
Thanks to all for their input/advice/help on this issue.


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