Max Pressure Cold vs Hot Pressures - How Much Is Too Much

FWIW, the past couple of years, Discount has been inflating car/truck tires to a few lbs over sidewall in their free air check bays. It's because the tires are no longer "cold", due to just driving to the shop. My van's tires are rated 35 psi cold, so they regularly go to 39, especially in the summer. I've asked them a couple times when preparing for a summer trip and a loaded van, to go to 40. If I'm 1-2 over the next morning, I can live with that. With my daughter, s-i-l, and grandkids in the car, I ain't taking chances!

Lyle

MFL wrote:
I think some of the tire inflation, disagreement, is due to talking about many different types of tire use. What works for cars, trucks, DRW trucks, motorhomes, and trailers, is not comparing apples to apples.

Most put the proper tires on their tow vehicle, and adjust as needed for load. I see some people buying way more tire than their trailer needs, then reducing pressure, way below max, when they should have just purchased the proper tire needed for the load, and aired for the load.

Jerry

I agree. My old Komfort, with 11,360 GVW, was placarded for D tires. At about 2550 lbs per tire, that put the tires UNDER the GVW; the rest is carried by the truck. Fine for most, but too close to the limit for me and, after I lost a tire in the 2nd year and another failure in the 4th year on the 2nd set of D's, I went to E's and ran 70-75 psi almost exclusively for the next 9 years and 2 sets. There were a couple occasions that I was running heavier than normal (extra ice, food and water) and I'd inflate to the full 80 psi. Using my temp "gun", the E's at 75 ran at least 5 degrees cooler than the D's ever did, and they were always inflated to 65 psi.

My current KZ, 860 lbs gross lighter at 10.5k, had D's and I replaced the original tires with a set of Endurance D's. So far, they're working well. I'd've gone with Carlisles to save some money, but Discount didn't have any and had none in their entire national inventory at that time. I was time-critical in that we had a camping trip planned and I only found the bad OEM tires (2) about 3 days before leaving.

Lyle

Walaby wrote:
I agree... it is load limit, and if you exceed the load by a pound you should go to the next higher rating. BUT, my interpretation of Cummins 12v98's post is even if I were at or below the appropriate rating, he recommends adding 5 PSI. Just strikes me odd that he (and others) are so adamant about following the chart, but then decide on their own to only take it as a recommendation and create their own chart (in their mind).

Just an observation, nothing more.

Mike

As I just mentioned I follow what I was taught by GY Tech Support!!! I can tell you with many thousands of miles I have always had perfectly even tread wear.

Walaby wrote:

Cummins12V98 wrote:
Over/under MAX has nothing to do with "PROPER" inflation. There is a reason for every tire there is a Load/Inflation chart.

Weigh your axles and add 5psi to what the chart recommends. This is per GY Tech support for when a person wants to use the brain GOD has given you instead of blindly airing to MAX sidewall pressure.

Im just curious.... if the chart is gospel, why go 5psi above what the chart recommends?

Mike

This is directly from GY Tech support. "When changing to a higher load range or wanting to have a better ride, better stopping traction and tread wear use the inflation chart and add 5psi".

They said to weigh each tire if possible as one side can weigh more than the other. The 5psi I assume is to compensate for one side weighing more than the other as most can't weigh each tire. They said "use the heaviest tire to determine inflation on each axle".

Never ceases to amaze me how passionate people get about things like tire pressure. You'd think Rv'ers were discovering the cure for cancer.

I agree... it is load limit, and if you exceed the load by a pound you should go to the next higher rating. BUT, my interpretation of Cummins 12v98's post is even if I were at or below the appropriate rating, he recommends adding 5 PSI. Just strikes me odd that he (and others) are so adamant about following the chart, but then decide on their own to only take it as a recommendation and create their own chart (in their mind).

Just an observation, nothing more.

Mike

Walaby wrote:
I'm just curious.... if the chart is gospel, why go 5psi above what the chart recommends?

Mike

Actually, the chart is a MINIMUM! Even says so! (Load Limit)

time2roll wrote:

Walaby wrote:
Im just curious.... if the chart is gospel, why go 5psi above what the chart recommends?

Better to be 5 over than 5 under. Can lose some air naturally or through a slow leak.

I agree. I just really don't understand the mentality of "thou must obey the inflation charts", but then recommend 5 PSI over said inflation charts.


Mike

Walaby wrote:
Im just curious.... if the chart is gospel, why go 5psi above what the chart recommends?

Better to be 5 over than 5 under. Can lose some air naturally or through a slow leak.

fj12ryder wrote:

"Jerry, the Fuzion came with 235/85-16, E-rated ST tires. Which were, I believe, rated for around 3,480 lbs., so the original tires were rated for about 21,000 lbs., still over the GVWR, and waaaay over my actual weight of 15,000 lbs. I actually considered going to LT tires when I had to replace those lousy ST tires. But the Sailun tires were cheaper than any of the other LT tires at the time.

I ran the OEM ST tires at 80 psi, max sidewall recommended pressure, and they failed in less than 2 years and 6,000 miles. The sidewalls were like tissue paper, they were so flimsy."

Thanks Howard! Having that extra axle sure changes capacity, and maybe lighter pin. Seems lots of changes in the RV tire world, some good, some bad.

Hope you are enjoying the new TH!

Jerry