How long have you run your tires on street with low PSI

[tjZ06]

I carry one of these in my center console and check tires and rim centers (bearings) at gas and rest stops during long road trips.

Good idea. When I was hauling heavy trailers all the time, especially behind 40k+ LBS 1600+ lbs-ft torque RVs I would hit the hubs on the trailer w/ a heat gun every stop. You could basically lock up a trailer wheel and never even notice in the RV...

-TJ

 

[MOAK]

I want to interject, the tire pressure listed on the tire is NOT the pressure you want to run. That is the absolute pressure to every be allowed.

If you air up to the MAX pressure then go out and run in the heat at highway speeds, the tire will heat up and the pressure will increase, possibly leading to a blowout.

The pressure you want to run is somewhere below the MAX pressure. I don't have time to go over determining that pressure in detail at the moment, but there is a common test called the chalk test or contact patch test. You coat the tread of the tire with chalk and drive a short distance. You then look at where the chalk is still on the tire.

The goal is to get good and even mating of the full width of the tire to the road. If you air up too much, you will wear out the center of the tire as well as have a vehicle that it very skittish and wants to oversteer.

If you under inflate the tire, you will wear off the edges of the tire prematurely and you will have understeer.

You have to find the sweet spot, and that pressure depends on the width of the tire, the width of the rim, the height of the sidewalls, the stiffness of the sidewalls and the load, and type of driving (curvy or straight). The shocks you have can even play into the equation over a long period. That is why you do a chalk test with your set of conditions.

My rig, running 35" tires BFG AT LO's works best with 26-28 psi. I am still experimenting with the new MT tires. They seem to be a lot more touchy.

All true, my tires say they will run 45lbs. That number is the maximum for maximum weight for each tire. In our old Jeeps, Ford Ranger and RAV4 30/32 . The cruiser with all the gear scales out at 7,000 lbs, hence 36-38. The trailer is 1500lb, tires at 24-26lbs. If I’m gonna haul firewood with the Ranger I’ll get em up to 34-36 a lot of folks make the mistake of pumping em up to the max & wonder why their tires are toast at 30,000 miles

 

[Ubiety]

Good idea. When I was hauling heavy trailers all the time, especially behind 40k+ LBS 1600+ lbs-ft torque RVs I would hit the hubs on the trailer w/ a heat gun every stop. You could basically lock up a trailer wheel and never even notice in the RV...

-TJ

On a road trip with the guys one of my buddies was pulling a bigger loaded trailer (UTVs) and grabbed his IR thermo to check the bearings; have kept one in the truck and used it ever since.

 

[tjZ06]

I want to interject, the tire pressure listed on the tire is NOT the pressure you want to run. That is the absolute pressure to every be allowed.

That is patently incorrect. The pressure listed on the tire is the max cold pressure. You absolutely can (and will) run higher pressures than that, if you set your tires there cold. I don't disagree it's the wrong pressure for *most* rigs/people, but it absolutely is the correct pressure for *some* people. My rig is over 10k lbs and I run my tires at/near the max cold pressure for pavement (especially extended street driving).

-TJ

 

[Deleted member 82267]

Just like TJ said HEAT!! The sidewalls flex and build a ton of heat at hwy speed. Heat will cause a tire to fail.

 

[MOAK]

That is patently incorrect. The pressure listed on the tire is the max cold pressure. You absolutely can (and will) run higher pressures than that, if you set your tires there cold. I don't disagree it's the wrong pressure for *most* rigs/people, but it absolutely is the correct pressure for *some* people. My rig is over 10k lbs and I run my tires at/near the max cold pressure for pavement (especially extended street driving).

-TJ

Hmmm, it is patently correct- the max load on a BFG (different brands and sizes may vary)285/75/16 is 3750 lbs each at 80 lbs, full inflation) That’s 15,000lbs GVWR, I’m curious, do you inflate to 80lbs and still get well over 50,000 miles out of a set?

 

[tjZ06]

Hmmm, it is patently correct- the max load on a BFG (different brands and sizes may vary)285/75/16 is 3750 lbs each at 80 lbs, full inflation) That’s 15,000lbs GVWR, I’m curious, do you inflate to 80lbs and still get well over 50,000 miles out of a set?

What I was saying was incorrect is that the rating you see on the sidewall is the maximum psi you should ever have in your tires. It is not. It is the max *cold*. If you set your tires there cold you will certainly see above that number once you've run down the highway, but that is perfectly safe/okay. This has nothing to do with sizes, brands, etc. DOT requires that max pressure on the sidewall, and DOT specifies it as a *cold* rating. FWIW I have run 80psi on other tires on this truck when I was still towing 17k+ lbs 5'ers with > 3,500lbs pin weight - but of course I did not get 50k miles out of tires towing that heavy -and- off roading on M/Ts.

My current tires (37x13.5-17" Toyo M/Ts) are rated at 4,300lbs each at 65psi. My truck with the camper on is north of 10k, but pretty evenly balanced (a bit nose-heavy), and obviously does not begin to approach 8,600lbs per axle. Still, I find the most even tread wear at 60-65psi cold, aka very close to the rated limit for the tire. Every tire will be different, it is not always the case that you *only* run the max psi at the max load. If my truck weighed half this much I don't expect I'd still find 60-65psi correct, but I don't think it needs to be 17,200lbs to wear best at 60-65psi either. The amount of sidewall flex at even 50psi is enough to tell me it's "not right" for my application *on road.*

-TJ

 

[MOAK]

What I was saying was incorrect is that the rating you see on the sidewall is the maximum psi you should ever have in your tires. It is not. It is the max *cold*. If you set your tires there cold you will certainly see above that number once you've run down the highway, but that is perfectly safe/okay. This has nothing to do with sizes, brands, etc. DOT requires that max pressure on the sidewall, and DOT specifies it as a *cold* rating. FWIW I have run 80psi on other tires on this truck when I was still towing 17k+ lbs 5'ers with > 3,500lbs pin weight - but of course I did not get 50k miles out of tires towing that heavy -and- off roading on M/Ts.

My current tires (37x13.5-17" Toyo M/Ts) are rated at 4,300lbs each at 65psi. My truck with the camper on is north of 10k, but pretty evenly balanced (a bit nose-heavy), and obviously does not begin to approach 8,600lbs per axle. Still, I find the most even tread wear at 60-65psi cold, aka very close to the rated limit for the tire. Every tire will be different, it is not always the case that you *only* run the max psi at the max load. If my truck weighed half this much I don't expect I'd still find 60-65psi correct, but I don't think it needs to be 17,200lbs to wear best at 60-65psi either. The amount of sidewall flex at even 50psi is enough to tell me it's "not right" for my application *on road.*

-TJ

Thank you for clarifying. Agreed- semis run 120lbs cold and 90 lbs on the steer axle. I’ve always assumed the “cold” was understood. Blow outs on tractor trailers are because of one of two things, underinflation or cheap recaps.

 

[Billiebob]

Hi!
First of all I´m sorry about my spelling and grammar, english isn´t my first language
with that out of the way...
Most of my overlanding trips have a mix of tarmac and dirt, and I´m wondering if I should air up for the tarmac bits in between
I´ll give you some context, I drive a 2016 VW amarok which weigths around 5800lb (it´s got steel front and back bumpers, winch and all my camping gear) I´m running 255/85r16 whichs is a 33x10 Yokohama Geolander MT003 LT
most of the trails I run at 25-20PSI and the streets bits at most are 15-20 miles but almost exclusively highway (60-70mph)
My question is should I be airing up and then down again, or can I run 25-20psi on the street and not worry about ir
I do have a power tank and my tires being so norrow it never takes me more than a few minutes, but it seems a bit excecive doing it for every strech of tarmac

let me know what you guys think!

Not sure of your vehicle but 5800# is not excessively heavy. My Wrangler weighs 4200#. I run 26psi ALL the time and I do 1000km a week on the highway, half of that towing 2000#. I'd not worry about running 25psi. The guys to ask about running 20psi are the guys selling you the Yokohama Geolanders..... and warranty would be the big issue. The internet and ANY forum will give you the worst advice. READ the tire spec...... talk to the guys who SOLD you the tires.

Tire air pressure is related to load and load rating. Check the tire spec for recommended tire pressure vs load. Lots of E Rated tires are rated for 85psi..... LOADED. But empty they run fine at 25psi. PSI generally affects how evenly tires wear on the highway. IF you ever have a warranty issue and the tread wear indicates you ran too low an air pressure the warranty will be void. Tread wear is the first indicator of running too low or high a tire pressure. Sidewall flex of an underinflated tire will generate heat and eventually.... or sooner..... lead to a blow out.

Read he tire spec..... talk to the guys capable of voiding the warranty...... in writing is best, ie email.

 

[Billiebob]

How low can you go on pavement,,,,, well......

If you want to go from zero to 300mph in 3 seconds..... this works