What psi should i run?

Chalk test is not an accurate test... Too many variables...
Did you know..Tires actually increase in diameter as speeds increase! This will give a false chalk line reading!
Don't do the chalk and make a bunch of turns...chalk wont give accurate reading because of inside/outside excess wear from turns...
Tire temp affects air pressure~

You can do this:
Are you an 'around town' driver? ok, do the chalk and drive around town!
Are you a freeway flyer? ok, do the chalk and drive the freeway!
Stick to as straight a section of road as possible.
This way you will get a more accurate reading for your driving style.
my .02 worth

 

Load Inflation Table.

 

Hello Guys,reading your stuff here.Need some help,not doing the chalk thing,this is my thought,correct me if I am wrong.My Truck had OE 215/70/15. On door PSI FRONT 30 REAR 33. Now I have 245/55/19 from a Highlander Limited reading on door FRONT 30 REAR 30 My wife 2012 Highlander has the same on door. I put on tires 32PSI due to the fact that the Toyota Dealer that install the wheels and tires said they would use 38,when checked it had 36,it could have been a bad reading, Anyway what I am trying to get is that 36-38PSI is to much and with 32PSI feel it runs much nicer,no bumpy or ruff ride. Let me know what you think,been playing around with manual on Tacoma due to the different sizes of wheel that is comes with and I think it sounds ok what I am doing. Have a 2012 TOYOTA TACOMA 4CILINDER DOUBLE CAB,again it came with 215/70/15 and now it has 245/55/19,got them at a local Toyota dealer and they looked to good. Checked everything to make sure they would fit and they look awesome,what a change.Found out here that these wheels would fit,so far no complain,the other thing is speedometer off,Toyota local dealer that install says that on my truck they have no way to calibrate,so I have back off of that.Like always thanks for help,let me see if I can put a picture of truck,still learning how use site,lol.

 

I GOT 275/65/18 GOOD YEAR DURATRAC DOUBLE CAP 4X4 TACOMA WHATS NORMAL TIRE PSI ? ANYONE PLS ?

 

Hello SodoScott,I have on a 2012 TOYOTA TACOMA OWNER'S MANUAL, this information not sure if will help you but I will try. P255/45R18 99V showing FRONT TIRES 35 psi REAR TIRES 35 psi wheel size 18x8JJ, P265/60R18 109H FRONT 29 psi REAR 29 psi Wheel size 18x7 1/2 J Not sure if this helps you.Also have a 2012 TOYOTA HIGHLANDER OWNER'S MANUAL I have P245/55/19 19x7 1/2J wheels and tires and I figure out around 32psi on front and rear. Manual says FRONT 30psi REAR 30psi also same psi on P245/65R17 105S My wife has this size on her Highlander. I installed at the dealer the 19" Highlander wheels and tires,Toyota Dealer said 38psi is good and when I checked it had like 36psi.Truck felt to hard on road and bumpy. Now it feels ok even though it is a 4 cylinder,it has 32psi. Take care. This is my truck.

 

Just .02 more cents, I have stock tires which i think are 265/60r17. The door says 29 front and 29 rear. They look like they are going flat. I bumped it up to 34 PSI all around. I like the ride alot better. It feels like it should.


Anyway just my .02 cents worth.

 

1) Check cold air pressure to start. Use the recommended psi on the sticker in your truck.
2) Go for a drive for at least an hour so the tires warm up. Min 30 min..
3) Check the air pressures. If your starting cold psi was 35 its should now be 39psi. No more! (The psi increases because the tire heats up)
If the psi goes more than 4psi you need to add air to the tire. A low tire will get too hot and blowout.
Air temps, speed, and loads all have an impact on tire pressure.

This method works on any tire or road condition. From rock crawling to sand dunes, or high speed you can set your pressures with this method.

 

Here is more information than you may want to read all about the 4 PSI Rule.
http://www.aawen4x4.com.au/index.php?option=com_content&view=section&layout=blog&id=1&Itemid=7

 

Thank you for this information. I was wondering why my tire PSI went up after driving. I always felt like the recommended PSI on the driver's door was too low because they look flat.

 

I don't know if anyone has seen this, but I thought it was pretty cool. Basically you take a chart to find what pressure you should be running per what load you are carrying and per your tire size. Here is the article http://www.offroadadventures.com/articles/view/id/509 and I thought this thing was cool as well http://tyresaver.parkertyresaver.com/tyre-inflation-range.php and here are some charts http://toyotires.com/tires-101/load-and-inflation-tables http://www.michelintruck.com/michelintruck/tires-retreads/load-inflation-tables.jsp http://www.tiresafety.com/images/Tire Replacement Manual.pdf http://www.barrystiretech.com/loadtables.html Hope this helps anyone confused about what pressure they need to be running in the tires.

 

Got a 06 tacoma. Running Yokohama Geolandar A/T-S 275/70R16. Looking for tire pressure front and back. Running 35 up front and 33 in the rear.

 

Thanks. On my way to adjust tires now.

 

Anyone running Michelin Latitude Tours....(summer tires)... I have a mounted set waiting for spring to go on the truck.... any idea what I should do for pressure?

Or is the chalk test the way to go...??

 

Check post #111, it has Michelin info in it

 

Idk if this was stated or not. But the method I use (since I live on a dirt road and dirt yard, and don't have a street close by to use the chalk method) I LIGHTLY spray the dirt down with a hose, then drive through it slowly after it soaks in a little, until I hit dry dirt and drive a rotation or two, and see how much sand or dirt sticks on. If it's too high or low you'll get a general idea. Beforehand I adjust it by eye to see how flat the tread is. Ideally that's all you're looking to do.
Also on a side note, if you ever get your tires serviced at any shop, be sure to adjust your pressure before leaving because every single time they air them up too high. I think it's kinda funny they don't know that larger aftermarket tires require different pressure than what stock says.

 

Oh another thing, for those of you that might not know, tire pressure changes with temperature dramatically. Especially for me in Az... But make sure you drive a distance before you adjust your pressure so they get up to the proper temp for normal driving. Or, get yourself a tpms kit like i did and you can adjust it on the fly. You'll never regret it. Ordered mine on Amazon and had my local big o install it. Orange Electronics was the one I got. Think the one on Amazon now is a newer version than what I have. But whatever you get is cheaper than what the shops charge for sure. But yeah it's sweet. Shows tire temps and everything.

 

I am running Mickey Thompson 285/75/R16 Baja ATZ Front tire pressure is 35 rear is 32 still noticing outside tread of rear tires not getting cleaned off. how low can I go on rear tire pressure without causing slipping?

 

I have 32 11.5 15, I run 30 up front and 28 in back (cold). So at night when it's cool it doesn't change a whole lot. It goes up a degree or two. So I end up running at about 31 up front and 29 in the back. At night the temps are affected too much. During the day is when I see a more dramatic increase. The fronts go up to 33 and the back about 30 maybe 31. But it changes so often that I was fighting to keep a steady pressure. But I think I found a happy medium. Which was the 30 front and 28 rear. 28 in the back seems low but if you think about it, there's like no weight in the back with our tacomas.
Now with summer upon us I'm gonna have to start adjusting lower for higher temps. I think last summer I was running 26 in the back and 29 up front. Which gave me about the same numbers after warm up to 28 in rear and 32 up front. So really it takes a lot of experimenting to find that perfect psi. But it never really is perfect.

 

Here's how I see it:
I consider it fact that the MFG recommended pressures are only for the stock tires and are typically setup to cover the maximum recommended load. For my purpose on my stock tires on my unloaded truck that means they are too high and ride like a basketball for my day to day driving. Recommended is 29F/29R. I run 28F/25R.

The max pressure on the tire sidewall, any tire sidewall, has zero to do with the proper PSI for the vehicle. It is just that, the max before the tire could be in risk of rupture. It is also typically the PSI where the tire can carry the most weight. If you are running anywhere near this pressure on an unloaded Tacoma, you are driving a basket ball.....bounce -bounce - bounce. You also have very little rubber on the ground and likely have reduced traction and possibly safety.

A given tire is designed to flex a certain amount and operate best with a certain number of square inches on the road. You get the correct contact patch for a given vehicle by adjusting the PSI based on the weight bearing on that axle. To much air equals not enough flex and to little contact area, thus reducing traction and possibly safety. To little air creates to much flex. To much flex can greatly increase tire temperatures leading to tire failures. This is what happened in the Ford Explorer tire issues.

Math facts that pertain here:
If you take the weight on a given axle, divide it by 2, divide that by the PSI and you will know how many square inches of tire are touching a hard even road surface.

With all the above, if you are running larger than stock diameter or width tires, it's a pretty safe bet your correct PSI will be lower than the stock PSI.

I have heard rumor that all tire mfg publish charts for this purpose. However, I have never been able to locate one. If anyone has access to this info, I would love to have a copy. With out that the calk method here makes sense to me but should be used with due caution.

Here is what we can do ... you may or may not want to do this. Take the max load rating of the tire, divide by the max PSI, this equals the square inches that will be on the ground with these figures. Now take the weight bearing of your axle, divide by two (for one tire), divide by the square inches above, and you will have the correct PSI for that tire on that axle with your axles weight.

Ain't math wonderful. Now does anyone know how much weight our various trucks have on each axle?

 

Adding to above:
If your tires and rim width are not matched up correctly, neither the calk method nor the math method will likely give you correct PSI readings.