Tire pressure

This week it's been in the 30s in the morning, and the low tire pressure light came on. I was surprised to see the sticker on the door jamb specified 29 psi, I thought it would be more. Then I realized according to the sticker the original tires were 245 75R/16. I have 265 75R/16. Only 2 tires were slightly low, maybe 27 psi, filled them to 30. Doing research I see various pressures depending on the load capacity for 265 75R/16 tires, from 26-36 psi. Would 30 psi be a reasonable pressure?

 

I generally run about 35 in front and 32 in the rear. If I'm going to haul something with a little weight, I'll air up the rears to about 35 as well but unloaded, that's too harsh a ride.
It will certainly ride better at 30-ish, but for tire wear and gas mileage, I always run 35/32. I check them regularly.

 

Ok for both replies. Doing research shows a 265 tire is slightly taller than a 245. That means less revolutions per mile but not necessarily better fuel economy. I was also a bit surprised when I bought this Tacoma, it's almost the same height as my '02 Chevy Silverado Z71. The Z71 has slightly larger tires than the base model, and stiffer springs. Due to that, it's a bit higher than the base model.

I haven't driven the Tacoma since I added air, last time I did that with another vehicle it took a while for the low pressure light to turn off.
Re: inflating to 35 lbs, I may do that at times when I haul firewood.

 

Its all dependent on tires, weight of truck, and what you are hauling. There is no one answer to rule them all.

I run 32/30 on my SL rated 265/75R16 Michelin LTX M/S's, If they were the LT rated ones id need to inflate more to get the same even wear.

 

30 psi is fine.

I don’t like topping off or airing up when I hook to my trailer.
I’ve kept anywhere for 30-35 psi in my tires since I have owned the truck. (13 years)

 

Ok - before checking the label I assumed they'd call for at least 32 psi, I think a former company minivan I had was 35 psi. I actually expected them to be down a bit more. I bought the truck in May and today 2 of the tires were right at 30 psi.

 

Anywhere 30-35 is fine. A little less if I'm going to be on dirt roads for a day

 

A chalk test will help confirm the right pressure.
But I’m too lazy and don’t care enough to do one.

Exact tire pressure isn’t something I worried about.

I think you’ll be fine with anything from 29-35 psi.
My gauge goes in increments of 5. I aim for the middle between 30 an 35, and call it good.

 

this subject has been beat to death, search around the forum. not a single truck is going to be the same psi. everyones set up is different. plenty of youtube videos show how you can find the right psi for your set up. i found a good one for mine using the chalk test and what i find comfortable. for my set up im finding that around 34.5 psi is good for my 265 ko2's on a 4 cynlinder access cab

 

Tire size shouldn't matter as to PSI. If you're using E rated tires it might make a small difference in how much air you use. Anywhere between 30 PSI up to 40 PSI will be OK. Even as much as 44 PSI. It just depends on how heavy you're loaded and other factors. I like to keep around 35PSI in my Tacoma tires most of the time. A bit more if loaded heavy, a bit less if off road.

I see you're driving a 2007. Those have sensors in the spare. My TPMS light came on earlier this week when it got cold. All 4 tires on the ground were at 35 PSI, but my spare was only 25 PSI. Aired it up and the light went off.

 

I am running 295s, E-rated tires.
I run 35psi, but I also have a 1000lbs of armor.

 

Needed cold pressure is dependend on load on tires, and max speed used.

Max speed is what you wont go over for even a minute, and is easy to determine for the situation, but be honest in that, so take a reserve in that, say 12mph more is 2 speedcode steps.

Load on seperate tires is more tricky, best would be weighing, but who does, and vary's in use.
The carmaker uses GAWR's for that, but already written here gives bumping when driving empty.

Now this "pigheaded Dutch selfdeared Tirepressure specialist" determined in time, that if 85% of the loadcapacity belonging to the pressure for 99mph real on tire, is the border for comfort.
That is why I use 90%, when calculate pressure for axleweight, so if weightdifference R/L the lightest side still wont go below 85 % and the heavyest side then 95% so still some reserve for pressure-loss in time,inacurate pressure reading etc.

Extra reserve is because your max used speed is lower then 99mph.

But you could drive slower when heavy loaded on a short trip( for instance that wood transport) so for that load and speed still enaugh pressure to prevent overheating of one or more tires.

This is the main goal of tire- and car-makers, when giving recomended pressure.
Only once overheated, the tire is lost, because little internal cracks are created, wich tear further in time, by the mechanical forces whatever you do after that. Then mayby only after 3 years that far that tires blows or treath seperates.
Then the real cource is long forgotten, and extremer situations at that moment are blamed.

I can make a pressure / axleload list for your tire with that 90% used for 99mph.
Your tires maxload is given for 99mph.
Then you dont need to add reserve yourselves or devide by 2, all done for you to make it easy.

For that give tire-specifications read from sidewal.
1 maxload or loadindex.
2. Kind of tire to determine the reference-pressure( yours 80 psi is E-load)
3. Speedcode, less important, from Q to V speedrated reference-speed is 160kmph/99mph, for reference-speed maxload is calculated by the tiremaker and given on sidewall.

I looked the system of, the tiremakers use for speed / maxload relation, and can use that to also give 90% used for 68mph ( speedcode K) for instance, so you can see what axleload it can have at same pressure, for transporting that wood at 68mph.
Then you dont need to adyust the pressure for such an incidental short trip.

 

It sounds that between 30 - 35 psi is a good range to be in. My son who was in the tire business, and who's eyes are better than mine found the max rating was in fact 44 psi. He also showed me how the front tire wasn't wearing evenly. There's probably a years or more worth of miles on the tires, but I may go to the original 245 size for (slightly) better fuel economy. But maybe not, he noted some dry rot. I may stay with 265s since at times I haul firewood.

Thanks for the note about the spare - didn't think to check that. I'm thinking that's what may have triggered the light, the 2 tires that were low were just marginally. For a monthly Preventive Maintenance for a company van I had, checking the spare air was part of the checklist, but I don't think that van had a sensor in the spare.

'Doing the math' is good IMO! And comfort as part of the calculation is a factor. Driving slower when heavily loaded may happen today - my neighbor has some wood leftover from a tree taken down.

Makes sense then to run 295s. Do you also have a cap?

 

Because of the 44 psi max cold given on sidewal, I assume its a standard load P-tire.
Those are allowed to carry the maxload upto 99mph AT 35 or 36 psi.
Googled the sise and found 119 loadindex in AT( all terain) and 116 loadindex in allseason tire.

Will use the 116 AT 36 psi for the list, so it never gives to low pressure. But check this on your sidewall. If different, I will make a new list. If you see on sidewall XL /reinforced /extra load its AT 41 or 42 psi.
Will make the list giving 90% of the loadcapacity for the pressure for 99mph behind the psi , and in front of 90% of loadcapacity for 62mph/100kmph. For that I highen up the loadindex by 6 steps so 122 loadindex.
I think fully loaded for a short trip, you can hold yourself to that 62mph.

But mention it if you want it different, can easyly put other data in my made spreadsheet for that.

265/75R16 SL 116 loadindex is maxload 2756 lbs for max 99mph.
LI 122 is maxload 3307 lbs for max speed 62mph.
62mph90%/ cold psi/ 99mph 90% = comfort
3532 lbs/ 20 psi / 2944 lbs /
3686 lbs/ 21 psi / 3072 lbs /
3839 lbs/ 22 psi / 3199 lbs /
3992 lbs/ 23 psi / 3327 lbs /
4144 lbs/ 24 psi / 3454 lbs /
4296 lbs/ 25 psi / 3581 lbs /
4448 lbs/ 26 psi / 3707 lbs /
4600 lbs/ 27 psi / 3833 lbs /
4751 lbs/ 28 psi / 3959 lbs /
4902 lbs/ 29 psi / 4085 lbs /
5053 lbs/ 30 psi / 4211 lbs /
5203 lbs/ 31 psi / 4336 lbs /
5353 lbs/ 32 psi / 4461 lbs /
5503 lbs/ 33 psi / 4586 lbs /
5653 lbs/ 34 psi / 4711 lbs /
5803 lbs/ 35 psi / 4836 lbs /
5952 lbs/ 36 psi / 4960 lbs / reference
6101 lbs/ 37 psi / 5085 lbs /
6250 lbs/ 38 psi / 5209 lbs /
6399 lbs/ 39 psi / 5333 lbs /
6547 lbs/ 40 psi / 5456 lbs /
6696 lbs/ 41 psi / 5580 lbs /
6844 lbs/ 42 psi / 5704 lbs /
6992 lbs/ 43 psi / 5827 lbs /
7140 lbs/ 44 psi / 5950 lbs / your maxcold
7287 lbs/ 45 psi / 6073 lbs /
7435 lbs/ 46 psi / 6196 lbs /
7582 lbs/ 47 psi / 6319 lbs /
7729 lbs/ 48 psi / 6441 lbs /
7876 lbs/ 49 psi / 6564 lbs /
8023 lbs/ 50 psi / 6686 lbs /
8170 lbs/ 51 psi / 6809 lbs / often maxcold

 

And go figure, it must be the spare that's low. The light is still on - now I just drove 3 houses down the street and back with firewood, but considering the 2 that were low, weren't that low. Looked underneath, and of course the tire is mounted so the valve is on the other side. Looked at the manual, I doubt lowering the tire will provide access to the valve.

 

I generally run 30 cold. Any more than that creates a harsh ride. But this is highly temperature dependent. I have my ScanGauge 2 set to display tire pressures in real time and keep an eye on that as the weather changes so I can get to this before getting the TPMS light.

 

You can flip it over and put it back, I keep mine with the stem down so it can be checked without lowering it.

Also once you get all the pressures set where you want you can "initialize" them using the button below the steering column (see your owners manual for instructions) this will set the initial pressure in the TPMS to what is currently in each tire, the light will then come on at around 3-6 psi below the set pressure. If you run different pressures in the front and rear you need to do the initialization each time you rotate the tires after you correct the pressures.

 

But.. if all your sensors are original from 2007 I bet the batteries are dead in at least a couple of them. Is the warning light flashing on startup? Or is it on solid?

 

Yes, stem down would appear to give plenty of access. The bolt holding it in looks quite rusted. May spray it with PB Blaster or something like that and let it sit for a few hours, or maybe a day.

Good tip re: initializing the TPMS - considering the wide range of acceptable pressures I wondered how the light was triggered.

 

No cap, built it to wheel and go camping.
I pull a 3500lb expedition trailer also.