Tire pressure

Topic: Tire pressure (Read 2611 times) previous topic - next topic

Tire pressure

September 06, 2015, 08:19:29 pm

I was wondering what would be recommended on my coach for tire pressure front and back. I'm heading in for service and than they can check my tires .
Looking forwards to your response
Rob

Re: Tire pressure

Reply #1 – September 06, 2015, 08:53:17 pm

If you don't know what each axle actually weighs or better what each corner weighs (with a tag drive and tag) then it is best to set the pressure at the pressure recommended by the tire manufacturer for the gross axle weight rating.

If you do know weights then use the highest of the two sides of an axle to set the pressure recommended by the tire manufacturer plus 5 lbs but not more than the max pressure.

I run close to max in the front because I think it is safer. Others may think differently.

Roger

Re: Tire pressure

Reply #2 – September 07, 2015, 02:14:23 am

I know my weights and still run max psi. more pressure = sharper handling, less worrying, and lower tire temps.

some sit aroudn and calculate psi based on weight. I run max recommended and drive. no worries. its been great for the 6k miles ive driven in 3 months of ownership on ancient 2007 tires.

Re: Tire pressure

Reply #3 – September 07, 2015, 02:24:20 am

I have always maxed the pressures without figuring the load since the sixties. Handles great, stops well and tires run cool.

Pierce

Re: Tire pressure

Reply #4 – September 07, 2015, 06:19:25 am

Max pressure equals poorer traction and more severe loads on suspension. Get your coach weighed and run the tire pressures recommended by the tire manufacturer.

Re: Tire pressure

Reply #5 – September 07, 2015, 10:20:39 am

It's slightly rougher ride at max (which I ran when I first bought my FT)

I run 100psi all around. It makes it simple to check, no wondering what axle is what. I installed Crossfires too....easy to keep eye on pressure: Amazon.com: Crossfire Dual Tire Pressure Equalization System, 100 PSI, one...

Max is 110 on my tires. 9600lbs front, 1800 lbs rear. Tossed all my notes, but 100 gives good safety margin for both front and rear.

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: Tire pressure

Reply #6 – September 07, 2015, 11:22:05 am

My Best Practice ... Weigh each axle and each end. Set tire pressure accordingly with a fudge factor.

I run 106 in the front and 96 across the single back based on mfr pressure/load charts + 5 psi.

We were just out in OR for a month. Someone posted that their weigh station scales remained operational even if the station was closed. They were right. I checked axle weights twice (very consistant) and the right side once to get four corners.

L-R in the rear were within 50 lbs. L-R in the front about 200 lbs heavier on the drivers side. Scales read to the nearest 50 lbs. Easy and free.

Re: Tire pressure

Reply #7 – September 07, 2015, 12:45:19 pm

Have not redone my old test I did hundreds of times when running the old ca Foretravel store as sales manager but it seemed to work then.

After countless discussions with highly opinionated owners some knowledgeable, some not so much about this I thought I found a way to help quantify on a quick term basis whether the air pressure in the coaches tires was correct.

Here's what we did.

Found nice white concrete and wet it to make a puddle and then drove through it onto a dry area.

As the tire(s) dried out and driving in a radius so the paths did not cross the pattern used to show lighter on the edges with higher pressure.

Zero idea if this works still. Better engineering now might keep the tire flatter at all normal pressure variations?

Lots of interest back then so took a drive in countless coaches to test them. Fairly sensitive back then. Five pounds easily changed the dry out pattern.

Oh of course a tire thread depth wear gauge works well to check wear?

I totally agree with Amos and would never run my tires at anything other than the charted weight/versus pressure that the tire maker recommended.

That being said if the mpg is for various reasons the most important thing to an owner running max pressures definately adds mpg. At least long ago.

Foretravel delivery drivers would call me and ask if they could increase the tire pressure for the 1369 mile drive to my store as it made them $20 more as Foretravel filled the tank for the drive out. Any refills were on them.

Foretravel shipped the coach with the tires matched to the weighed empty coach back then.

I find on the internet that my new tires are good for around 250,000 miles on an 18 wheeler to go from 19/32 thread depth to 6/32" which I understand is the minimum you should run.

So 12/32" over 250,000 miles won't show much short term on a tread depth gauge but over long enough some may be able to quantify the pressures they are using with actual facts?

Unless the engineers have gotten so good as to have identical across the tires wear regardless of the pressure which I doubt.

Be nice if a bunch here would buy a cheap gauge and measure their tires to help all of us here?

Opinions are nice but I prefer facts. Did this long ago with hundreds of owners.

Guess it's time again.

Running long ago on the center rib as was posted made a rougher ride and the coach handled funny and wandered more in winds.

Tire tech and better shocks might cover this up anymore and the pressure variations may make zero wear differences.

But I doubt it. If enough here show me a full contact wear patch and exactly the same handling and ride quality at a pressure over the manufacturers charts I like everyone here would like better mpg as long as no safety issues or ride quality reductions are the penalty.

Five dollar tire thread depth gauge would add lots to any tire pressures mentioned would it not?

My old tires were all over the map on wear.

Re: Tire pressure

Reply #8 – September 07, 2015, 02:00:11 pm

When you say the tires last 250,000 miles are you including miles after regrooving? My Michelin XZE 275/80 R22.5 tires measure about half worn with 30,000 miles on them. Last summer I saw a similar tire on the front of a fairly new garbage truck with 46,000 miles on it and the mechanic replaced it because he said it was worn out, but it still had over 1/16" tread on it. Garbage trucks do a lot of tight turns but this tire didn't have any strange wear patterns. The mechanic didn't think 46,000 miles was an abnormally short life for that tire... so I was thinking my tires would go somewhere between 50,000 - 100,000 miles. Yes, I already know my tires are old and everyone on this forum thinks I should replace them, but I'm gonna run them until they wear out. They don't even have any weather cracks. At the rate I've been traveling I'll probably wear them out as soon as three years from now... unless they really do last 250,000 miles?

Re: Tire pressure

Reply #9 – September 07, 2015, 02:16:05 pm

Quote from: Roger & Susan in Home2 – September 07, 2015, 11:22:05 am

We were just out in OR for a month. Someone posted that their weigh station scales remained operational even if the station was closed. They were right. I checked axle weights twice (very consistant) and the right side once to get four corners.

Washington State has the same deal. I don't see many scales in our travels, but checking with a friendly State Patrol officer might be of help.

Re: Tire pressure

Reply #10 – September 07, 2015, 02:52:19 pm

They had A WEIGH WE GO at the last grandvention in TN. They weighed us as we were leaving. It was a great deal.

After weighing with my 2 scooters, which will make me the heaviest on the front axle, so I run 115 on my fronts. I should be 110 but I add 5 pounds. My rears I have at 100 and the tag at 90.

Re: Tire pressure

Reply #11 – September 07, 2015, 03:09:34 pm

As far as the wear miles I going by the over the road truckers report of miles.

Matches the Michelin warranty of 7 years/700,000 miles with the carcass being good for three redoes.

Search Xza-3's or maybe it was on the Michelin website as far as owners reports.

A lot commented on that kind of life.

Obviously the exact setup and use can change this to a great extent.

Half the reason I spent the money for the Michelin's were these reports and the high value for dated but low wear tires in the future.

My tire guy says they use them for runouts on trailers. In other words use up the tread versus worry about recapping them.

Re: Tire pressure

Reply #12 – September 07, 2015, 03:38:31 pm

I would think 100-200k on tread for a good quality tire is to be expected for long haul over the road.

Re: Tire pressure

Reply #13 – September 07, 2015, 04:09:35 pm

Quote from: Caflashbob – September 07, 2015, 03:09:34 pm

In other words use up the tread versus worry about recapping them.

Amen to that. I blew a cap one time; it scared the pucky out of me!

Re: Tire pressure

Reply #14 – September 07, 2015, 04:24:16 pm

I just measured my new Michelin spare that's never been used and it has about 19/32" tread according to my dial indicator. My six Michelins with about 30,000 miles on them average about 15/32" on them. So I guess you're right and they should last longer than 100,000 miles at this rate. Darn it, I was hoping to be the first RV owner in the history of the world to wear out a set of tires.

Re: Tire pressure

Reply #15 – September 07, 2015, 04:42:50 pm

I enjoy reading about folks who KNOW that XX psi is correct but add 5 psi for good measure. Kinda makes me thing that the XX psi sinn't correct.

Re: Tire pressure

Reply #16 – September 07, 2015, 08:19:38 pm

Hey Larry, a little wiggle room helps some times. We left 100+teens in Montana at 6,500' for sea level and 50's - 90's in Oregon to 32° this morning at almost 7,000' in the Tetons in four weeks. When we head south in the winter I air up for ambient temps in MN (-30° Feb, 2014) and two days later it is 70°. I had to let air out every day. 0-5 psi over spec is OK with me. A little overinflated is better than under inflated.

I have load range G tires soon to be replaced with LRH. A little more air in the LRG stiffens up the sidewalls some. Won't need it so much with the LRH tires.

Tire story ...

A guy in an older Prevost pulled in near us a few days ago. Coach seemed to straighten up to level and plumb until engine was turned off then sagged as I watched to about 4" off level side to side. Then he gets out some ramps made from 6x8 and proceeded to drive the front tire on one and the outside rear drive tire on another. Nothing under the inside drive and nothing under the tag. 6x8 was about 3" narrower than the tread width. I have neve seen a side wall bulge like his rear tire did. I really expected it to just blow out. He left today. Good luck with that tire.

Re: Tire pressure

Reply #17 – September 07, 2015, 08:24:51 pm

So now let's talk about your leaving in -20 temps. Roger, my boy, gotta get going sooner. I was in MN for three winters in the 70's and leave for Florida in early October. Don't like cold!

Re: Tire pressure

Reply #18 – September 07, 2015, 08:46:46 pm

It was -30°, really. We are OK with the cold up to a point. It is pretty miserable adding air to all six tires at -30°. With the coach in the barn (or as Brad M calls it, the coach house), the AquaHot on preheating the engine for a day or two and the inside of the coach as well, the exhaust out throught the side port in the barn and the coach plugged in, starting is easy. We let it warm up a while while final connections are made with the toad, lights are checked, the barn is locked the house is double checked and we are off slow and easy for about 15 - 20 miles to let stuff start to move and limber up. And then we are off. Of course it takes two days before the long johns come off.

For us it is all about the weather on our route south. Cold is OK, it is only two days to warm. Ice or snow? We just stay put and wait for a few days. Never in a hurry here.

Might be cold in the winter in MN but the summers are nice. Visitors are welcome.

Re: Tire pressure

Reply #19 – September 07, 2015, 09:47:43 pm

Quote from: mike leary – September 07, 2015, 04:09:35 pm

Amen to that. I blew a cap one time; it scared the pucky out of me!

reminds me of a time I blew a front right steer on a bridge...best Bridgestone tire money could buy! luckily noticed a little bulge in the side wall about the size of a half a pencil while at a lumber mill loading green timbers destined for Puget Sound Naval Shipyard. While crossing a bridge in Olympia headed for the tire store instead of taking the on ramp to I-5 northbound she blew! luckily for the foot and a half curb held me from going over the rail...

Re: Tire pressure

Reply #20 – September 07, 2015, 10:04:37 pm

Quote from: Roger & Susan in Home2 link=msg=207802 date=1 Good luck with that tire.[/quote

Seen a few of those myself, would have liked to warn them but.......Hard on the wheel bearings, as well.

Re: Tire pressure

Reply #21 – September 07, 2015, 10:26:42 pm

That's right Mike, hard to know how someone will react sometimes especially when they think what they are doing is just fine. If they ask for my opinion I will say something otherwise stay out of harm's way.

Re: Tire pressure

Reply #22 – September 07, 2015, 11:49:08 pm

Quote from: RRadio – September 07, 2015, 04:24:16 pm

I just measured my new Michelin spare that's never been used and it has about 19/32" tread according to my dial indicator. My six Michelins with about 30,000 miles on them average about 15/32" on them. So I guess you're right and they should last longer than 100,000 miles at this rate. Darn it, I was hoping to be the first RV owner in the history of the world to wear out a set of tires.

Thank you for the factual info.

How's the wear pattern? Straight across? What pressure versus weight?

If I had a ten spot for every tire pressure discussion I have had with rv owners I would have a much newer coach.

Used to the snickers from the pros who know better. Countless times. Foretravel ships every coach since the 80's set for the weight as far as I know.

And fmca weighed coaches and adjusted the pressure to match the load on each tire since the 80's.

But what do they know.....

Re: Tire pressure

Reply #23 – September 08, 2015, 12:07:13 am

Radial vs bias ply? That makes a difference on how the tire sits?

Re: Tire pressure

Reply #24 – September 08, 2015, 12:49:15 am

Quote from: lgshoup – September 07, 2015, 04:42:50 pm

I enjoy reading about folks who KNOW that XX psi is correct but add 5 psi for good measure. Kinda makes me thing that the XX psi sinn't correct.

That extra five psi is for insurance. Just in case of a slow leak, more loading, or lower cold temperatures. Safer to be high than low.

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