I been thinking about this one for awhile: do you go by what the manual or sticker says or do you go by the sidewall and subtract a bit of pressure?

I say and always have been taught that the only time you should inflate your tires to what the manual says is when your running stocksize tires (maybe even the same OE tires). This is b/c that measurement is derived from using only thier OE tires, this means if you had 33" BFG at's and your vehicle came with 235x75x15 and the sticker says 35 psi your gonna be sorry and runining good tires by underinflating them and runing the outer edges of the tread.

Overinflation leads to runing the middle of the tire, underinflation ruins the outer edges or commonly called cupping.

Here is how I see it:
The general rule is to take the max inflation, say 50psi and drop it 5-8lbs or so. The easiest way to check if your doing it right is to take a piece of chalk and make a line across the tread and then drive about 10 feet. Check to see where the line rubbed off and adjust inflation.

I didnt even bother to do that with my T100 and 31" AT's at 50psi max. I just dropped 8lbs off the bat when I checked it. The previous owner had them inflated to 37ish, sure the ride was supple but I was wearing the tires more than I should. The fact of the matter is the tires were designed to be run on a variety of vehicles, no way a F50 running the same tires is gonna be the same as my truck will be.

Everyone will say different but thats how I do it. Every vehicle is also different, the T100 is alot bigger and heavier than an older runner, taco or pick up is when using the same tires.

 

I've been told that no matter what the size, the tire pressure is to remain what the door jamb sticker says. I currently have my 33x10.5's running at "stock" pressure. I had them a lot higher, but changed it...

 

In street trim I run 45 psi in my tires and they seem to be wearing well. I also carry quite a bit of weight though (with tools, gear, spares, etc.). I agree that it depends on vehicle and use. However, I would recommend running as much pressure as you can on the street and still keep even wear. Also, IMO most stock pressures are underinflated even with stock tires and weight. CJM, good advice!

 

So what is that 35-38 psi? Try the chalk test and see how you fair.

Like I said what the door jamb says is for thier stock Original Equipment tires only, since you mounted bigger ones I bet they are underinflated.

 

I have some ideas on selecting a tire pressure on the web page below:
http://www.4crawler.com/Diesel/Tires...roperInflation

Hard to give one answer, different tires will have different requirements and max. inflation pressures.

 

Excellent post 4Crawler, great info!

 

Yeah different sizes are for different tire.. the sitcker is for oem tires, size and style.. Therefore if you even change load rating, not size, you will have a different psi requirment.

Do not set 33's at what the sticker says blindly...

The max psi on the side of a tire is for max weight too... so if your tire says 2270@50 That means if you runs your tires at max your set up for a rig that weighs 9080 pounds.. toyota are not that heavy.

Take a look at this post too, I put a ton of info in there...

 

https://www.yotatech.com/forums/f123/recommended-air-pressure-235-75-15-a-97053/

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