Rear Tire PSI when towing?

I'm not familiar with the 245s that come on that model. Instead I'll use the 265s the come on the 2018 TRDs

Max pressure is 51psi and max load is around 2500lbs.

Stock weight is around 4450 and max payload 1150lbs for a total of 5600lbs. I'm going make a lot of assumptions here but let's say that at max weight the truck had a 50/50 distribution. This works out to 56% of the max capacity of the tires.

Tire pressure and weight scales linearly. Since the stock tire pressure around 60% of the max pressure, I would guess that Toyotas tire pressures were defined at max payload.

Again, lots of assumptions, but I don't think it's necessary.

 

@Hook78

You know....its always possible to generate an exception.

My reply was specifically for the OP's situation. Certainly not intended for every conceivable scenario.

I didn't assume the OP was intending to tow his camping trailer for long distance on a beach.......

Oh well.....you are certainly most experienced.....


Based on OP's post #1, he will have roughly 600 lbs as cargo (tongue +gear) and people in the truck. Most likely below the maximum load capacity of the truck. So no need to fiddle with tire pressures.

Mr. Hook....what would be your counsel for the OP's situation??

 

My point is simply that the placard is not a one-size fits all from a performance perspective, just a safety perspective.

Obviously I’m not talking about pulling a camper on the beach, I’m providing an example at the other end of the spectrum where lower pressure is appropriate.

Yeah the OP’s setup isn’t THAT heavy but over a long distance, it’s heavy enough where increasing the rear PSI will result in increased performance and reduced wear. That’s it.

 

I find these threads interesting across different forums, as in, Everyone has their opinion and is right.

I'll add mine as well.. I DO adjust tire pressure just accordingly if needed. That said, the only vehicle I've ever owned that actually put air pressure adjustment in the manual was the Land Rover.

Reference.... This is from my Land Rover owners manual (not to be confused with the Tacoma). Yes, she did have a fat (heavy) ass on her in stock form.

 

Lots of differing opinions in forums. Funny I see the same name giving bad advice, getting quoted, called on it and defending it.

Anyway, I do a lot of towing. Everything from light kayak trailers to track bikes on a flat trailer to a 18x8.5 enclosed car hauler with a Jeep inside. I don't use my Tacoma to tow heavy loads since I have a diesel super duty van.

My advice is to compare the feel of the ride between not towing and towing. When I tow several thousand lbs, I put the e rated tires to 80 in the rear, 70 in the front. If the tires are at 60 front and rear, the ride is spongy, the van doesn't track as straight down the highway (kind of a wompy light side to side rocking) and definitely less of a crisp tracking feel through curvy mountain roads.

Tires are designed to work at a specific temperature range. If you run them too low, the sidewall flex will generate excessive temperature. You may not get a blow out, but if done regularly, it will cause the rubber to lose its essential oil and will dry rot sooner, lose grip prematurely (even with plenty of tread), wear the edges of the tire faster than the center, etc...

Feel your tires after a decent drive. Notice the temp of them. Do the same when towing. If you feel a tire abnormally warm/hot, the pressure is too low. When I fill up at gas stations, I touch the trailer tires as a quick check

Personally, I raise my tire pressures when towing. How much depends on which vehicle I choose to tow with, load rating of the tire, distance towing and speed of travel.

Also, I've never heard of tires blowing out from running at max recommend pressure. Only if they're old and need replaced anyway...

 

For both trailer tires and truck tires, mfg’s will publish a load/psi chart…. Usually buried in the tech info.

One can also do a chalk test on tires when hooked up.

I usually run mine 40 rear 38 front when towing. Between tongue weight and supplies in bed I’m usually near max payload. I do use a weight distribution hitch, which (allegedly) transfers some weight to front axle.

most importantly, when I gas up I check tire temperature of both truck and trailer tires (also trailer bearing hubs). If running in 100* weather I use a thermal gun, instead of the back of my hand. Temps on the sunny side can hit 120-130.
psi usually only increases 4-6 on my tires when running. The max pressure on tire is cold pressure.

Blowouts are usually due to tire heat in excess of 180*, generally due to under inflated tires flexing. The high temps breakdown the tire and cause high pressures.

NEVER reduce air pressure after driving. If your tires are too hot, stop to let them cool a bit (they wont cool fully while you eat). If you absolutely must keep going add 5 psi to where they are to stiffen them up a bit and go 10-15 mph slower to help them run cooler.

 

If anyone here is dying to get a scientific answer on this, ask Barry @ http://barrystiretech.com/index.html

I've spoken with him in the past regarding the chalk test for setting tire PSI and learned some interesting things about it. He definitely knows tires more than most people you find on internet forums.

 

I towed hundreds of thousands of miles with my own and company trucks since the ‘70s. I’ve never adjusted tire pressures when towing. If stock size run what it specifies on the door frame tire decal. The engineers didn’t just put it there because they were bored.
If not stock tires, do the chalk procedure, determine proper unloaded pressure then go.

 

I haven't pulled a boat in years but often pull a loaded down utility trailer. Never increased tire pressure on the truck. And never ran max PSI on any of my trailer tires.

And those of you that run max PSI on trailer tires...do you worry about blowouts? I have a spare but possible blowouts have always freaked me out as it happened once when I was young. Scared the shart out of me. Recent trip I pulled a loaded trailer down to Del Rio area (about 200+ miles 1 way) and had trailer tires about 10 lbs shy of max PSI when I set out. They were almost at max PSI when I arrived at my destination. So I always run about 10 lbs shy of max...is my point.

 

I don't know if all trailers are like this but mine has a sticker on the tongue with the appropriate cold tire pressures meaning when the trailer hasn't been driven and the tires are cold. In my case, it's 60 psi and the tire max written on the sidewall is 60 psi. So to answer your question, I don't worry about blowouts from running the max/recommended pressure because of course the trailer manufacturer knows pressure increases as you drive and they take that into account.

 

Yep mine is an old farm trailer with layers of paint and rust. No stickers left. But I hear you on the sidewall max psi.

 

Here’s a good article I found on the subject and it basically says to run max sidewall pressure and explains why. It touches on pressure increasing 2-4 psi once warm so if I had to guess, yours jumped 10 psi because they were extra warm from being under inflated. Just food for thought.

https://www.google.com/amp/s/www.boatingmag.com/properly-inflating-boat-trailer-tires/?amp=1

 

Thank you sir. And that makes sense about under inflation. During that trip outside temps were 100+ too.

 

Not at that tongue weight.