New tire pressure ?

[Aage]

Thanks very much to you all for your thoughts on this question.

The majority of you run your tires at the maximum pressure, or very close to it, while a couple of you seem to be following (roughly) the Goodyear Guide (Thanks, 2dabeach for posting that!).

Gene, I hope you finally got some sleep after the motorbike incident, because you sure confused me with your talk about guages, load ratings, and vehicle mfgrs vs tire mfgrs' ratings. Now -I- won't get any sleep!

I'm think that I will try 55 lbs for the first while and keep a real close watch on temperatures. I may also go to 65 lbs just to see if there is any discernible difference.

Let me sleep on it

[Gene]

Aage, it made perfect sense to me at 3 am. I did get back to sleep just after the motorcycle got started again. If I wake up in the middle of tonight, perhaps I'll post further explanations, factors, errant thoughts and other educational matter, though I can do it anytime, thus…

Also I'm contemplating how our trip and the predicted path of a tropical storm seem to intersect in New Orleans next week?

But back to tires—it seems to be this: we may be obsessing over this. Perfection is impossible with tire pressure due to inaccurate gauges, temp changes, and disagreements over what is important and how to interpret it. The more I read, the more I'm thinking that using the load tables and setting tire pressure according to them is the way to go. I periodically check tread depth and if the center is wearing faster, lower the pressure several pounds; if the sides, increase pressure. Tread may be talking to us and we should be listening (or measuring).

Gene

[Minnie's Mate]

The more I read, the more I'm thinking that using the load tables and setting tire pressure according to them is the way to go.

This is certainly the BEST method, but not everyone will have access to individual tire scales. In my case, there is a truck stop at the Interstate exit about six miles from my home. I don't believe they have anything except a CAT scale. Certainly you can separate the tongue weight and the weight on each axle just by the location on the scale and if you disconnect to get the tongue weight on a separate part of the scale. However, I don't know (limited knowledge here) of how you could park on the scale to get individual tire weights. So for me, I go by the CAT scale print out and figure I get pretty close to the right distribution.

BUT, I also consider my driving habits and, based on the GY load charts, I up the pressure to the max. Like I said earlier in this thread, I have camped for four years now and have put nearly 30,000 miles on these tires. By keeping the tires at the max, there is less sidewall flexing. I also put 33 spray from Camping World to condition the sides. This product gives UV protection and ozone protection. By using our Airstream on nearly a monthly basis, the tires get more flexing to redistribute the waxes and oils in the rubber than those that store their Airstreams over the winter or maybe go on one long trip per year. At least this is what I think is happening.

[thecatsandi]

Originally Posted by dstalzer

I run 65 lbs with the GY Marathons and have had no problems. My TV has load range E tires with max 80 lbs and Ford recommends 75 for these tires. I sometimes wonder if running at the max is really ok when starting out at 65 lbs when it is 70 degrees in the morning, and especially when it gets to is 100 degrees or more in the afternoon.

Dennis

The cold tire pressure will vary about 1 PSI for every 10 degrees of temp change.

[safari 28]

Update on chinese made marathons. Just pulled in to the KOA in Eureka. A very tough drive along the trinity going north west out of Reno into Susanville/ Redding and man some real work for the entire rig. Fingers crossed, they have over 10k on them and look great. Always 65 psi or close. I have not seen a streamer in a park for 2 weeks. Can't blame you, 60 mph winds in mountain roads. The f150 took a beating on this one. Fun stuff and she handles like a dream. I passed everything from semis to pushers, these things are really a gem of an old design.

[Mikethefixit]

Robbi
Just read the sidewall of the tire . Whatever it says DO IT.
IF it says 65 psi, run 65 psi. Its that simple. I got into trouble with TV tires by not running the specified pressure stamped in the sidewall. It was more neglect than anything,not closely monitoring tire pressures at least once a month. It cost me a set of tires.

[Ag&Au]

Originally Posted by CrawfordGene

And you will get them, Aage.

The prevailing wisdom (no comment as to whether it is "wisdom") is to inflate tires as Airstream recommends. But does Airstream know what it's talking about, or is it just taking the safe, lawyerlike approach, and saying the maximum is right?

..............................................
Of course, there's "cold pressure". Temps can vary a lot during a day, especially the further you are from the coast. People say to check pressure during the coldest part of the day, a time which may be very early in June, long before you get up. A tire in Key West may increase 5 pounds during the day, 15 or more in Arizona. Overpressure will mean a harder ride, so maybe cold pressure means "whenever I start driving compensating for which side of the trailer is in the sun".

I'm going back to bed. The motorcycle is gone. I hope I've clarified things.

Gene

Hi Gene,
As long as you went to so much work, I thought I would post this table(attached) so you can take your altitude into consideration.
If a tire is inflated by the beach in southern California and then driven east until reaching the summit of a 10,000 foot mountain pass, the tire pressure will increase by 4.596 PSI from the altitude change alone. In addition, perhaps we should also look at the weather. Driving from a high to low pressure weather system could conceivably up the tire pressure another couple PSI.
This link give some interesting information about tire pressure change with temperature. Tire Tech Information - Air Pressure, Temperature Fluctuations
I'm beginning to think that inflating tires is just a ball park procedure.
Regards,
Ken

[Ahzmyrah]

Wow, this ain't rocket science. I am a former tire dealer and truck fleet operator and I have adjusted many, many tire failures for most of the major manufacturers. Tires fail primarily because they are either underated for the load they are carrying or if rated properly they were under inflated. Simple as that. Remember the Ford Explorer tire failures a few years ago. The tires spec'd by Firestone/Bridgestone were properly rated for the vehicle but the Ford engineers recommended a lower tire pressure for a "nice ride". Most people don't check there tire pressures unless a tire is obviously low. Load the vehicle up to max or tow a trailer and you have problems.

There is a lot of relevant information in this thread. The basics are these:

Know how much your rig weighs and that includes your tow vehicle. If you can't weigh it look at the owners manual to find empty weights and estimate what you are adding...it's ok to estimate too high.

Use a tire rated to carry a load heavier that your max load out plus at least a 10 or 15 percent safety margin.

It doesn't matter what A/S or your T/V manufacturer recommends. Inflate the tires to a pressure that will safely carry your calculated load. There are tables out on the internet posted by tire manufacturers that give pressures vs. load carrying capacities.

Don't get too anal it takes the fun out of things. Try checking your tires cold on a hot sunny day. First on the shady side of the trailer and then on the sun soaked side. Tires are black and they absorb heat. The sunnyside tires will have a significant difference in pressure from the cool side. The same thing happens when you go down the road. What do you do now?

We are in the middle of a trip right now that has included 118 degrees in Death Valley below sea level to 20 degrees in the Rockies at 9000 feet 10 days later. I run 225/75R15 load range E tires rated for 2880 lbs at 80 lbs pressure. I have them inflated to 65 lbs cold, check pressures before traveling and visually check and feel the tires and wheels at fuel and rest stops. We have close to 20k miles on them right now with minimal wear.

[Gene]

I agree that getting anal about tires will drive you crazy. I had considered adding altitude to what I had written before, but decided it was getting looney enough. I think comparing the load on the tires with the tables and making any adjustments as above is the way to go. I expect everyone will come up with a different number for a specific tire on a specific trailer (or TV) but I think 67-70 is about right from my tires on my trailer.

Gene

[safari 28]

Gene, sitting in Arcata Ca and heading south. I am convinced the forum can do strange things to simple minds. Speaking of myself only. I am outside staring at my chinese made marathons and hoping they do not blow at 65psi. Its a problem, The corrosion issue is some how fixable, just get the damn thing painted by Andy some day. I am worried big time about the frame being encased in the belly pan and crumbling like the bay bridge some day. But tires, just full of air, and the worries we have are what people experienced only in the 30s for tire technology. It seems the trailer service application side of the business was on the back burner for the past 50 years or so.

I am heading to Pasadena, hope they make it.

[Gene]

Arcata is a nice town. We had a real good lunch at a Chinese restaurant on the town square several years ago. Next time we're on the Pacific coast we have to spend more time there.

I hope you make it to Pasadena and Colorado Ave.

Gene