Stock rim pressure limit?

[Friggin Idiot]

I've gotten fed up enough with the factory Bridgestones that I've started pricing out some new tires. One of the local shops who I've used to for years and trust told me something that made me stop and think. I wanted to see if anyone else has heard similar.

Basically I was told that I can't run the LT265/70R17 size because the factory rims ('14 TEP) can't handle the 80PSI max pressure that the tires could. I did a quick search, which of course was useless, as was calling the not-so-local dealer. Are they blowing smoke up my a$$ to get me to buy rims as well, or are they dealing straight?

 

[2014 Warthog]

I've gotten fed up enough with the factory Bridgestones that I've started pricing out some new tires. One of the local shops who I've used to for years and trust told me something that made me stop and think. I wanted to see if anyone else has heard similar.

Basically I was told that I can't run the LT265/70R17 size because the factory rims ('14 TEP) can't handle the 80PSI max pressure that the tires could. I did a quick search, which of course was useless, as was calling the not-so-local dealer. Are they blowing smoke up my a$$ to get me to buy rims as well, or are they dealing straight?

Can't answer that outright but were you really planning on towing something with 1000 pounds of tongue weight?

There is no reason you would likely ever need that much pressure. Regular highway would be 40-44, towing or a very heavy load maybe up to 55... Typically Only a 5th wheel or a very heavy duty hitch setup would need max pressure on an LT tire. Like a giant work truck or something.

 

[Friggin Idiot]

I don't think I'd ever have a need to run that high of a pressure no, but they refused to order the tires for me for that reason. Last set of LT's I had on the old Bronco never saw above 50psi, although they were mounted on steel rims.

I'm not sure a stock 4Runner could handle 1klbs on the tongue without bottoming out. The largest tongue load I'll probably have to handle is 350lbs.

 

[wfo9]

I don't think I'd ever have a need to run that high of a pressure no, but they refused to order the tires for me for that reason. Last set of LT's I had on the old Bronco never saw above 50psi, although they were mounted on steel rims.

I'm not sure a stock 4Runner could handle 1klbs on the tongue without bottoming out. The largest tongue load I'll probably have to handle is 350lbs.

They are dumb asses....(just trying to cover their ass and follow procedures....) Find another place, there is 0 concern.

The max pressure has nothing to do what is required on your vehicle.... It cracks me up that people that do this for a living still don't understand tires. The higher the load rating, the less pressure you should need.

Also. sounds like you were looking at an E rated tire. Not really necessary. D would probably be a better option just because of the weight savings and better road manners.

 

[1engineer]

Ha! Tires would blow long before rim lip. Rims are rated for load not pressure. Find a new shop dude.

 

[Friggin Idiot]

Also. sounds like you were looking at an E rated tire. Not really necessary. D would probably be a better option just because of the weight savings and better road manners.

Correct, sadly the few AT tires I've been looking at, none come in C/D load ranges for the stock or +1 sizes. So the choice is a P-metric, or LT E load. While I don't think I'd ever need the E rating, I want a tire built stronger, and sturdier than the P-metrics. While I'm not to the winch-required level of off-roading yet, I do tend to be hard on tires.

Thank you guys for the input, I thought that had sounded wrong. Rubber giving out at 80psi but an aluminum alloy that can't take it? I just a hold of the accessories guy at the not-so-local dealer, and he explained a few things. I think the shop may be more worried about the TPS. Apparently the 'Yota service guys just reset the optimum pressure and thresholds to the higher psi ratings when putting on LT aftermarkets. I'm wondering if this shop was worried about that instead of the actual rims.

I've heard of a few guys on here leaving the TPS out when putting on new wheels, has anyone left them in and had them reprogrammed as such?

 

[nevada]

Ha! Tires would blow long before rim lip. Rims are rated for load not pressure. Find a new shop dude.

not true.
lots of wheels have pressure limits.

often times its stamped/cast into the wheel.


OP, pull a wheel and check the back side.


if its true they aren't rated for 80psi, they are absolutely correct, and shouldn't sell you tires rated that high. its a liability issue, as theoretically, someone could read the side of the tire, and put too much pressure in.

 

[3wbdriver]

if its true they aren't rated for 80psi, they are absolutely correct, and shouldn't sell you tires rated that high. its a liability issue, as theoretically, someone could read the side of the tire, and put too much pressure in.

Which happens to me about every other time I have mine rotated for service. I get home and air them back down from the 44 PSI my sidewalls specify to the more normal 35 - 38 I prefer. IF I don't think to specify that when I pull in for service.

 

[harper7]

Correct, sadly the few AT tires I've been looking at, none come in C/D load ranges for the stock or +1 sizes. So the choice is a P-metric, or LT E load. While I don't think I'd ever need the E rating, I want a tire built stronger, and sturdier than the P-metrics. While I'm not to the winch-required level of off-roading yet, I do tend to be hard on tires.

Thank you guys for the input, I thought that had sounded wrong. Rubber giving out at 80psi but an aluminum alloy that can't take it? I just a hold of the accessories guy at the not-so-local dealer, and he explained a few things. I think the shop may be more worried about the TPS. Apparently the 'Yota service guys just reset the optimum pressure and thresholds to the higher psi ratings when putting on LT aftermarkets. I'm wondering if this shop was worried about that instead of the actual rims.

I've heard of a few guys on here leaving the TPS out when putting on new wheels, has anyone left them in and had them reprogrammed as such?

Plenty of people running stock wheels with e-rated tires on here and you should never have a need to run them at max pressure of 80psi anyways. I run my E's at 44psi .

They have a Discount Tire close to you over in Collinsville or Broken Arrow and most likely know what they are doing. You can order the tires online through them or calling them direct to order and they'll have them there waiting to be installed,not to mention they match anybodies low price with free rotations and TPMS setting if needed.

The TPMS's won't even have to be messed with just changing tires. They have a default low setting of about 26-27psi for the warning ,no matter what tire,load range and pressures you run and that threshold cannot be adjusted,no matter what the dealer says.

 

[Friggin Idiot]

OP, pull a wheel and check the back side.

Just managed to do this before the last of daylight.
Markings on the back of the wheel are:
China M3
13 (has 11 dots inside 12 squares next to it)
Toyota APK
J DOT
17x7 1/2J 15

Then closer to the bolt holes are cast numbers with other things stamped next to them. (Cast: Stamp)
1: 1J5
2: Y
3: H1M

Made in China... go figure. Wheel size and offset, but the rest, I have no idea.

 

[1engineer]

not true.
lots of wheels have pressure limits.

often times its stamped/cast into the wheel.


OP, pull a wheel and check the back side.


if its true they aren't rated for 80psi, they are absolutely correct, and shouldn't sell you tires rated that high. its a liability issue, as theoretically, someone could read the side of the tire, and put too much pressure in.

I don't think I misspoke.I know Split rims like some trailer wheels have max pressure ratings. One piece and alloy and steel don't that I know of. Bending forces yes. If you have some documentation though I would love to see it. I will make a few calls tomorrow.

 

[wanderMT]

I don't think I misspoke.I know Split rims like some trailer wheels have max pressure ratings. One piece and alloy and steel don't that I know of. Bending forces yes. If you have some documentation though I would love to see it. I will make a few calls tomorrow.

Hope you find an answer and report back. I have never heard of wheel damage from normal pressures, (up to 80psi). I'm sure there is limit but assumed it was well beyond normal. Also always thought the split rims were to keep tire on wheel under high pressure, not issue with wheel strength. Have seen lots of broken alloy and bent steel, but doubt tire pressure played role.

 

[marshal]

Just managed to do this before the last of daylight.
Markings on the back of the wheel are:
China M3
13 (has 11 dots inside 12 squares next to it)
Toyota APK
J DOT
17x7 1/2J 15

Then closer to the bolt holes are cast numbers with other things stamped next to them. (Cast: Stamp)
1: 1J5
2: Y
3: H1M

Made in China... go figure. Wheel size and offset, but the rest, I have no idea.

there is only one company left in america that casts aluminum wheels, and only 2 left that forge them. all aluminum wheel production for the most part was moved to china in the last 15 years. smelting is a dirty business and the EPA doesn't look kindly upon it.

 

[wfo9]

Correct, sadly the few AT tires I've been looking at, none come in C/D load ranges for the stock or +1 sizes. So the choice is a P-metric, or LT E load. While I don't think I'd ever need the E rating, I want a tire built stronger, and sturdier than the P-metrics. While I'm not to the winch-required level of off-roading yet, I do tend to be hard on tires.

Thank you guys for the input, I thought that had sounded wrong. Rubber giving out at 80psi but an aluminum alloy that can't take it? I just a hold of the accessories guy at the not-so-local dealer, and he explained a few things. I think the shop may be more worried about the TPS. Apparently the 'Yota service guys just reset the optimum pressure and thresholds to the higher psi ratings when putting on LT aftermarkets. I'm wondering if this shop was worried about that instead of the actual rims.

I've heard of a few guys on here leaving the TPS out when putting on new wheels, has anyone left them in and had them reprogrammed as such?

The size you are looking for has several C rated options available. Probably 2 of the most popular ATs around Goodyear Duratrack and BFG K02.

I'm not trying to talk you out of E. Its just that load rating does not really = durability and has nothing to do with offroad capability. Load rating is just how much pressure the tire can take. It's possible to have an E with a weak sidewall...Generally Es are stronger, but there are 40" C rated tires that can take just about anything off-road, but they are not constructed to handle 80psi...

 

[marshal]

[MENTION=106176]wfo9[/MENTION] you're almost 100% right. The primary difference outside of capacity is the rubber composition in the tread. e rated tires use a much different composition than lesser rated ranges. Generally they are much harder with higher silica content for longer service life carrying the heavier loads they are designed to. An e rated tire should well outlive an identical lesser rated tire driven in identical conditions

 

[AudiTech]

The higher the load rating, the less pressure you should need.

That's not nessesarily true. When I switched from factory 20's with the recommended pressure of 32 PSI all the way around to E rated LT275 K02s, BFG themselves said in order to keep the same load capacity of the stock tire at their recomended pressure the E rated K02s need to be at 35 psi to match the same load. (I think they said it was 1973 lbs for the stocker at 32 psi, the new tires would be 2000 lbs at 35 psi)

 

[nevada]

Just managed to do this before the last of daylight.
Markings on the back of the wheel are:
China M3
13 (has 11 dots inside 12 squares next to it)
Toyota APK
J DOT
17x7 1/2J 15

Then closer to the bolt holes are cast numbers with other things stamped next to them. (Cast: Stamp)
1: 1J5
2: Y
3: H1M

Made in China... go figure. Wheel size and offset, but the rest, I have no idea.

after a bit more reading, it seems as tho they also are sometimes stamped inside the air chamber. so the tire would have to be dismounted to see it.

I don't think I misspoke.I know Split rims like some trailer wheels have max pressure ratings. One piece and alloy and steel don't that I know of. Bending forces yes. If you have some documentation though I would love to see it. I will make a few calls tomorrow.

I looked, but couldn't find anything solid. just hearsay.
but, I do know that when I was busting tires for a living, that I did in fact see pressure ratings stamped on wheels. 65psi comes to mind. but I was unable to even find a picture showing that.

Which happens to me about every other time I have mine rotated for service. I get home and air them back down from the 44 PSI my sidewalls specify to the more normal 35 - 38 I prefer. IF I don't think to specify that when I pull in for service.

exactly what I was meaning.

 

[mo_mo]

I didn't see a max psi rating on the inside or outside of the 17x7.5 stock FJ rims I mounted. If you want the real answer, then Toyota or whoever designed your rims, will have to tell you. We can guess all day long for example: road bicycle rims run way over the max pressure rating of E rated tires and those rims are thin in comparison. They are also lightly loaded in comparison, so pressure isn't the only thing at play here.

 

[1engineer]

after a bit more reading, it seems as tho they also are sometimes stamped inside the air chamber. so the tire would have to be dismounted to see it.

I looked, but couldn't find anything solid. just hearsay.
but, I do know that when I was busting tires for a living, that I did in fact see pressure ratings stamped on wheels. 65psi comes to mind. but I was unable to even find a picture showing that.

exactly what I was meaning.

I didn't see a max psi rating on the inside or outside of the 17x7.5 stock FJ rims I mounted. If you want the real answer, then Toyota or whoever designed your rims, will have to tell you. We can guess all day long for example: road bicycle rims run way over the max pressure rating of E rated tires and those rims are thin in comparison. They are also lightly loaded in comparison, so pressure isn't the only thing at play here.

Alright. I spoke with an engineer this morning and he said all the wheels he has ever designed (I have designed a lot of things but never wheels) were designed to SAE specific standards. I specifically asked him about deformation of the flange due to over pressurization of the tire. He said they design the wheel for load carrying (this is a off highway application) and the tire pressure is not enough to cause the flange to deform. He said they don't even consider that because the area of the tire acting on the flange won't exert enough force to cause bending.

What this means is I have no documentation at all. I did a search that included SAE and I only found tire issues. No wheel issues at all. I read through all the SAE abstracts and found lots of material specs and fatigue testing procedures but no mention of pressure limitations on wheels. To download the complete SAE specific spec is $72.00.... for each spec!

So with all that being said I still say the tire will fail from over pressurization before the wheel and a typical burst pressure is around 200 psi for a tire.
Take this with a grain of salt as again, I have never designed wheels nor tires and have no documentation to prove nor disprove this.

 

[Friggin Idiot]

Thank all you guys for your help! I thought they were giving me a bunch of hooey. Then again now that I think about it, I wasn't talking to my usual guy, I was talking with the guy they give to all the soccer moms and octogenarians who come in. I'm guessing not all employees have the same understanding of what's really going on!

Of course this has made me revisit the P-metric vs LT debate, even though I've gone through this several times in the past couple weeks. This is the first time I've really done the math on this.

The P tires will more than support the max GVWR of 6450 lbs. According to the sticker on the interior drivers side B pillar that's to be distributed 3000 lbs front, 3450 lbs rear. Meaning 1500 lbs/tire on front axle, and 1725 lbs/tire for a max loaded vehicle.

Now given the manufacture spec for the P rated tire of max load 2535lbs. Even accounting for the 10% reduction as required for use of P rated tires in SUV/LT applications, that's 2281lbs, still more than the max GVWR would require at 1725lbs.

Jumping over to the LT E rated max 3195lbs at 80psi. The 1750lb requirement for max GVWR is barely half of that tire can do (53%). Assuming a linear relationship between tire pressure and load carrying capacity, at max GVWR the appropriate tire pressure would only be ~43psi. Of course that won't save me if some idiot fills the tires to max pressure during a rotation.

So both tires have more than enough ability to carry the load. The LT will win durability hands down no question, more tread to start with, heavier duty sidewalls, etc. They also look beefier and better. Handling and ride comfort will go to the P metric. Stability is a question mark. Would the LT will be slightly more sure-footed as a result of the stiffer sidewalls, or less because it would be more likely to slip than to have scrub like the P?

Being honest about how I use my vehicle, off road puncture considerations are rather low. Most of my off road driving is in quite sedate grassland or established trails. And while I enjoy the occasional trip off road, most of my time is spent on pavement as a DD. Now the road I drive as that DD is rather rough, severely potholed and always littered with dirt/rock and other debris. It has already claimed 2 P tires from my former car with sidewall bruises and slices from potholes and debris, so I'm more likely to get a puncture on road than off of it. This is the fun of driving past a quarry and a garbage dump to work. So I don't exactly need an LT tire. But the beefier look and longer life makes me want an LT. The fact that the tires I'm looking at only come in P-metric or LT load class E makes it interesting as I like a smooth ride. I'm hoping that the suspension and KDSS will take up the slack and ride much smoother than that old Bronco suspension when I went from P to flotation tires on it.

The size you are looking for has several C rated options available. Probably 2 of the most popular ATs around Goodyear Duratrack and BFG K02.

Yes, that may be so, however neither of these are on my short list. The KO2 is too new for a proper review, and I've heard many complaints about the Duratac for road noise. While I understand moving from a highway tire to an all terrain means more road noise, and more again for a P to LT conversion, I'm trying to minimize this. Also I'm starting the ball rolling to move north before winter comes again, so snow/ice traction will be a major concern. It will very likely be one of the first two, but my short list contains:
Hankook DynaPro ATM RF10
Toyo Open Country II
Cooper Discoverer AT3
Dick Cepek Fun or Trail Country (possible but not likely)