I brought home a new Toyota Tacoma that has tire pressure monitoring sensors. When I checked the Taco's tire pressure with the same electronic gage I check the bike tire pressure with, the knuckleheads at the stealership had all the tire between 45 and 50 psi. Spec on the door is 30 psi all around. So I let out air pressure until the digital gage read 30 psi - much nicer ride.

I dug into the manual and found how to select the TPMS mode display and it showed all tires read 33 psi - cold. WTF. SO I dug out two different mechanical tire pressure gages and rechecked all 4 tires again with both mechanical gages and the digital display gage. All tires are sat overnight cold and all of my gages read 33 psi and the Taco's TPMS display all shows all tires are 30 psi.

Not a big deal for the Taco but it sure got me wondering about the bike tire pressures. I recently watched a Dave Moss tire pressure YouTube vid and his process is to set the cold pressure to whatever PSI will raise the hot- after 45 min of normal fun riding, pressure 3 psi.

I'm now more confused than usual. With my digital gage, per DM technique (I'm betting HUB will disagree with Moss but hopefully he will engage here) my tires are set at 37 psi which raises to 40 psi after 30 min of twisty mountain roads. But based on what the Taco TPMS data shows I may be actually setting the initial bike tire PSI at 34 ??? high for the track but low for the street.

I dont have a way to calibrate anything, just a bunch of tire pressure sensors that are different. I understand the technology in the TPMS and kinda think I should trust a new tire pressure sensor vs. gages in my tool box.

Anyone have any knowledge on calibrating a gage or two?

Confused Rudy

We sort of walk over to the tire jobbers, ask to check our gauge against theirs, magic mark on the gauge glass +2, meaning, we are low 2 pounds against the jobber's gauge and we add 2 more pounds if theirs reads 30, we finish it at 32 on our gauge.

I'm told what pressures and write them on the side of the truck or on my hand. They all vary from tire jobber to jobber. They come back with the light ocean air ripple effect of that water surface. No gumballs. Only gumballs are at the edge of the tires.

It would be easy to check if Moss is right. He's have to set the pressure and when the bike comes right off the track, you test pressure change. Riding back to the pits would cool off the reading, What I get out of thermodynamics is you can calc the highest temp via formula. So if I understand it correctly, 3psi is all the heat of the peek, or, that's all she wrote. Gotta remember too, that's air rushing past, cooling the tire off, stop and go traffic cooling. It might climb higher if you were full race. And then again, lots of lefts and that cools down the right side and you lose the front if too cold.

4u, psi does make a difference. Too high a pressure up front and you toss it... ask me how I know. The way to do it junk science wise, use the one gauge as base. Every time the test is made, up the tire with the base gauge. That one loss on the push/pull into/away is going to throw off the next gauge, sure, but it will show who is out of range if any.

I think air pressure is a crapshoot anyways. I would be interested in seeing out of say five different gages how many would read the same. Now thats without saying that everytime you try a different gage your decreasing psi in whatever tire your using.

Agreed. I have a couple and they don't read he same. I haven't recently tried the third one against those because it's a built in gauge on a tire chuck but when I last used it, I believe it was different than the little pen ones I now take with me to the gas station air hose I use. I noticed my cold pressure change by at least a couple psi after the bike sat in the garage on a hot day compared to a cooler day. The same is true of a cold check of oil level. ten degrees makes the oil expend enough to raise the level. I would bet my tires increase more than 3 psi after I ride. The outside of the tire is hot after I get done riding, I would assume the air in it is about the same temp. Gas expands even more than liquid. I run my tires at 25 psi in the summer and when I take off, the steering feels heavy. After a 40 minute ride when I'm coming back to the garage, I don't notice that heavy feeling anymore.

My 2 mechanical gages and my digital gage are all 3 psi low compared to the 4 TPMS in the wheels, I tend to think the tpms is closer to real than my 3 gages. In about a week I get new 17 in TRDS wheels and a bit taller off road A/T tires. When I get them installed at the Firestone dealer I plan on asking their jobbers to comparer my 3 gages to their. Given, these are min-wager workers so I might not get a lot of good info

What do the NASCAR or IndyCar or IMSA cars use when 0.5 psi makes a big difference? is there some calibrated $$$$ gage out there

Dave Moss method and the logic works good for bike tires, regardless of the absolute PSI lower it until you get to the 3 psi rise point - regardless of the gage you use, as long as you always and forever use it it works.

33 psi vs. 30 psi is 10% difference, that a big deal and really bugs me there is not a simple way to be sure.

WRT nitrogen, dry N is great cause no water from the compressor enters the tire, a great thing.

And as a final note, when I set the Taco tires at 30 psi based on the TPMS after a normal drive the TPMS all show a tire pressure of 33 psi - same as Dave Moss recommends which means the correct heat due to friction is working with the tire setup.

For street I try for 3-4 psi diff and for track I try for 5-6 psi diff. Unless using
warmers.

Using nitrogen is a great way to go do to consistency between tire changes, moisture
content from differences from compressed air will change your cold tire settings from
tire change to tire change.

Seems most people refuse to educate themselves on this matter and will argue that
the 42psi or what ever setting on the required DOT safety rating for "MAX load" is
where you are supposed to set tires. I've heard it over and over.

On vehicles I go for even tire wear.

Like on my truck. When Discount Tire mounts a set of tires
they set them to max psi of 65psi all around.

Since it's a diesel it has a lot of weight in the front
and most of the time the bed is empty. For best tire wear I end up
55psi in front and 45psi in the rear unless I'm hauling something.