What I Learned Playing With Tire Pressure

[Dean2]

So prior to deciding to buy AlpHaOBD I was messing around trying to see how low I could set my tire pressures without setting off the low tire pressure warning lights. Door sticker for my 18 inch rims and factory Transforce AT tires is 65 rear and 60 front.

First off, I have Selectable Tire Inflation Assist along with the regular tire inflation assist. Setting the tire pressures presets on both user selectable presets, at 40 front and back will activate the fill alert when you hit 40 pounds while inflating. Despite some other threads on here, it does NOT keep the low tire pressure alert on the TPMS from alerting to a low tire. So effectively if you air down below the set thresholds it still alerts.

I did find that I could set the tires to 52 pounds all around and the low pressure alert does not activate. If I go to 51 on the rear, the low alert activates. I have not yet figured out just how low I can go before the front tires activate the alert but I am assuming it should be 5 pounds lower than the back. Since the published weight versus inflation for the Duratracs I am running is 45 front and 40 rear it means to set the tires to the proper pressure the low tire alert would always be on. To air up enough to keep it off, means the tires act like a basket ball and make the ride far rougher than it needs to be.

For anyone that doesn't want to buy the gear to reset the TPMS thresholds I hope this info is useful.

 

[Riccochet]

And once the low pressure alert is triggered you'll need to air up to at least 55 front and 60 rear in order for the warning to clear.

 

[Dean2]

And once the low pressure alert is triggered you'll need to air up to at least 55 front and 60 rear in order for the warning to clear.

Absolutely true. In fact I just aired them up to 60 and 65 to shut them off the easy way, before trying lower pressures again.

 

[Jimmy07]

I have not yet figured out just how low I can go before the front tires activate the alert but I am assuming it should be 5 pounds lower than the back.

The alert comes on at anything lower than 20% below the threshold. So if 60 is the threshold, the alert will come on when it falls below 48.

 

[Dean2]

The alert comes on at anything lower than 20% below the threshold. So if 60 is the threshold, the alert will come on when it falls below 48.

Cool. That matches what happened with the rears when it went off at 51 but not 52. Exactly the 20% you talk about. Thanks, learn something new everyday.

 

[Dean2]

So, learned something else today. With the temperature warming up, I needed to let some more air out of my tires. Set tire assist to on, set selectable tire pressure assist from the apps page, at 45 front 42 rear, select and save and proceeded to let about 10 pounds of air out of each tire. With the start button in the run position but engine off, the horn honks when you hit the selected preset inflation on each tire. Your 4 way flashes run while this process is active. Damn these trucks are getting smart.

Still sets off the low tire warning but makes airing down dead simple.

 

[Dean2]

Fixed the low tire alert by resetting the thresholds using AlphaOBD. Can now run 40 rear, 45 front, no more dingy, dingy. Interestingly, the new thresholds show up in the Selectable Tire Fill Alert system as now being the max pressure. You can select lower pressures for the alert for when you are filling or lowering the tire pressure, but not higher ones. So, in light of that I set the front threshold at 50, and rear at 45. Low tire alert will go off at 40 and 36 respectively.

 

[pacofortacos]

Fixed the low tire alert by resetting the thresholds using AlphaOBD. Can now run 40 rear, 45 front, no more dingy, dingy. Interestingly, the new thresholds show up in the Selectable Tire Fill Alert system as now being the max pressure. You can select lower pressures for the alert for when you are filling or lowering the tire pressure, but not higher ones. So, in light of that I set the front threshold at 50, and rear at 45. Low tire alert will go off at 40 and 36 respectively.

I need to do mine, do you know what page of the alpha thread those instructions are on?
Or is it pretty easy to find?

My 1500 setpoint is 43 so a cold day drop to 35 trips it - I generally run around 40 psi.

 

[Dean2]

Go to BCM for your year. Scroll down. It is very near the bottom. Says something like TPMS limits. Dead simple to change. Didn't need the 4 digit pin on my 2021 for the new limits to stick.

 

[Dean2]

Bump, in light of all the recent discussions on tires, towing and tire pressure.

 

[Mike Wenrich]

Is selectable tire inflation assist an option when buying a new vehicle? I'm not familiar with this and have not seen it as an option selection. And maybe cannot do it CA where I live.

 

[Dean2]

Is selectable tire inflation assist an option when buying a new vehicle? I'm not familiar with this and have not seen it as an option selection. And maybe cannot do it CA where I live.

I amin Canada and it came on my 2500 Laramie. It was not something I intentionally ordered but it could have been listed in a package and I never noticed.