Choosing the right air pressure for your non-stock tires

There seems to be a million different opinions out there for what air pressure is best for X size tire on X vehicle. I've done plenty of searching and found this guide from Toyo that makes selecting a good starting point much easier.

On this link, there's an inflation table link that will download the file in PDF format. Lots of reading if you want to understand better, but I'll break it down to basics.
http://toyotires.com/tires-101/load-and-inflation-tables

1. Somewhere around page 14, you can start looking for the stock type/size tire that came with your vehicle. Check your door jamb for the recommended tire pressures, and find those pressures on the columns next to your tire size. It may not be exact, but you should be able to calculate what yours might be.

2. Take note of the load weight listed for your stock tire/pressure. Some are different for front and rear.

3. Keep scrolling down till you find your new tire size. Find the column with the closest load weight to your stock setup, then scroll up to see what psi matches it. Again, it won't be exact, but should be pretty close.

When I did this for my 285's, it said 35 psi would be about right. The chalk test proved that this was almost dead on. I ended up with 36 psi after chalking them. For the 255's I'll be putting on, it says 43 psi will be what I need. So I'll start around 45 psi and chalk it from there.

EDIT: The chart was right on again. Turns out my perfect psi is 42psi with the chalk test.

I run my 255s at 43. Seemed to be the guidance of other owners who did the chalk test. I am to lazy. I look forward to your results. The newer TPMS on the FJs alert low tire pressure when it falls a little below 40. I can't explain why, but this may only be for the 16" wheels. There was a recall on the TRD wheels about 2 years ago. Dealt with this, or should I say resulted in this.

Brian wrote:

I run my 255s at 43. Seemed to be the guidance of other owners who did the chalk test. I am to lazy. I look forward to your results. The newer TPMS on the FJs alert low tire pressure when it falls a little below 40. I can't explain why, but this may only be for the 16" wheels. There was a recall on the TRD wheels about 2 years ago. Dealt with this, or should I say resulted in this.

The Tacoma actually has a TPMS reset button that allows me to set it at whatever tire pressure I want. I can set it for 16 psi if I don't want to look at the light on the dash when off roading

I remember that my TUndra had a reset button...too bad there isnt one on the FJ...either way it doesnt matter with my aftermarket wheels..NO TPMS on them puppies...so light just stays on when i have them on the truck...

Oh yeah, well ... I have an arm rest!

I run 35 in my 285 duratracs, and used the stock valve stems on my aftermarket rims. My light doesnt come on until I hit about 25.

Brian wrote:

Oh yeah, well ... I have an arm rest!

as do i!...im running about 40 in my KM2s...i just feel comfy at that psi...good breaking no real wander...soft enough for speed bumps...

I dont have the tpms, but I run my km2s at 40 and put 200 miles plus a week on the highway towing.
They are riding smooth fairly quiet, and wearing proper.

I'm running 34 PSI in my 295 75 16 BFG AT's. Chalk test shows this is about right. The TRD wheels they're mounted on are a little narrower than most aftermarket wheels which might cause a little more of a center tread bulge which is reduced with lower pressure.

Im running my 285/70/17 GY Duratracs at 42psi... anything less than that and it feels like Im driving a boat.

Turns out the 43 I calculated from the chart was nearly spot on. Chalk test shows 42 psi being just about perfect.

MadToy wrote:

Turns out the 43 I calculated from the chart was nearly spot on. Chalk test shows 42 psi being just about perfect.

Sweet. It took me forever to find a good pressure but I think Im finally dialed in well.