PSI range on TPMS? May 22, 2022, 07:51:33 pm Question about PSI fluctuations on the TPMS driving from Santa Maria back to the Bay Area on Friday (cooler weather, not a hot day up 101]. before leaving Santa Maria, I checked PSI in the morning, before sun hit tires (actually still foggy, to get ‘cold’ pressure readings) Front tires were at 60, rears around 71 - 72. Using the Viair, inflated to 66/67 front , 78 rear. After driving on 101 for a short while, TPMS alarm beeps, 91 PSI one of the rear dualies. Others were within 1 or 2 PSI (88/89/90) seems the default alarm is set to 90. Eventually all 4 rears hit 90-91 during the drive, (ranging 86 to highest of 92) Even though the ride felt fine, stopped to look at tires, thinking maybe should let a little air out, but decided against it, and just kept driving. Psi never went above 92, but most of the way stayed in 87-90 range. (Readings on the fronts were about 80, alarm did not sound) Is this normal? Should I let a little air out of all the tires or just increase the alarm threshold, say to 95? And how is ‘cold’ defined when you check & inflate tires in the morning? Temp was in the 50s the morning I did this. Thanks! Daryl
Re: PSI range on TPMS? Reply #1 – May 22, 2022, 09:37:44 pm There’s quite a few discussions on tire pressure on just this Forum. One of the more thoughtful ones is One more time: Tire pressure .I adjust tire pressure based on winter temperatures, summer temperatures and altitude while the tires are cold in morning. And of course I’ll check tire pressure on travel days. If the tire pressure is a few PSI different from my target PSI, I don’t bother to adjust them.Tire pressure can reach as high as 156 degrees before a blow out according to several on line sources. I think I set our TPMS temperature alarm at 135 degrees. I found the following information on the internet which might answer the increase in PSi due to heat. “The normal temperature increase over ambient is in the 30°F to 60°F range so I would expect to see a 6psi to 12psi increase in a tire starting at 65 to 70 psi. Now if you checked in the early morning while the day was still cool and then were driving in the heat of the day when it was 20°F hotter then we might need to add another 4% so we might see a 16% increase.”I hope this is helpful. 1 Likes
Re: PSI range on TPMS? Reply #2 – May 23, 2022, 12:53:29 pm thanks for the info! Looks like I really don't need to be concerned about that '91 alarm' reading :-) Daryl
Re: PSI range on TPMS? Reply #3 – May 23, 2022, 02:39:09 pm Daryl, on our first trip after installing the TST system, we had a high pressure alarm go off. It was mid-morning in late September on I-40 just east of Barstow, having left Tehachapi about an hour and a half earlier. Kind of freaked me out so I stopped and let some air out which, in retrospect, wasn’t necessary. I also turned up the alarm setting a little higher. Didn’t have any issues the rest of the trip to Arkansas and back.I still need to work on dialing the correct values in.
Re: PSI range on TPMS? Reply #4 – May 23, 2022, 04:06:43 pm thanks Greg, Ill be setting the alarm higher next time I'm at the rig! Daryl
Re: PSI range on TPMS? Reply #5 – May 23, 2022, 04:46:35 pm One of the first things I did was set more reasonable alarms than the default for trucks, basically 60 psi for low, 95 for high. And I think 120 for temp, though I’d have to look.Finally weighed my rig after getting tires five weeks ago, figure my load was close to travel load. I knew I was too high at 75 / 85, but figured a few miles around the Bay Area was ok. Based on weight, should be more like 65 / 75Got to experience the “fast leak” alarm while letting air out, so I know that works.
Re: PSI range on TPMS? Reply #6 – May 23, 2022, 09:07:28 pm Thanks Dave, I think I’ll do the same with the alarm settings. BTW, guess whose LD I saw in Milpitas when we dropped off ours on Friday afternoon?!😉
Re: PSI range on TPMS? Reply #7 – May 23, 2022, 09:16:40 pm Quote from: LazDazGuy - May 23, 2022, 09:07:28 pm BTW, guess whose LD I saw in Milpitas when we dropped off ours on Friday afternoon?!😉Yep! Picked up early Saturday morning for the drive up to AM Solar. 1 Likes
Re: PSI range on TPMS? Reply #8 – May 24, 2022, 09:25:32 am Quote from: Dave Katleman - May 23, 2022, 09:16:40 pmYep! Picked up early Saturday morning for the drive up to AM Solar.How did the install go?
Re: PSI range on TPMS? Reply #9 – May 24, 2022, 01:21:35 pm I’ll let you know on Friday when it’s done, but got an update, they are able to put in 4 batteries (400ah) as well as 5 170 watt panels (850) by removing the TV antenna that I’ll never use.
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