Tire Fun On First Long Trip

daveinfl · 06-19-2014, 02:33 PM

We set out from Orlando going to Branson, Mo. All was uneventful until the tread blew off one of our tires at about 300 miles into the trip (see picture). We had Goodyear Marathons ST225/75R15 inflate to exactly 65 PSI.

We bought our 2010 2619 used from Dream RV in Florida. The tires looked like new. In fact they still had the new markings on the outside of the tire. No signs of dry rot, or other noticeable issues. I had done a bearing job just before leaving on our trip. Hubs were not hot and the wheel didn't feel hot.

Made radical decision to change both tires and the spare. Found a wonderful dealer that worked a lot with travel trailers. He had the Marathons ... but said we would be better served with an E rated 10 ply steel belted radial tire. His explanation was sound I thought. So we purchased them. We ended up with Akuret ST225/75R15 HF188
Max Load 2830 LBS
80 PSI
DOT 83B4 HFA

I stopped several times traveling the rest of the way to Branson and felt the tires. They didn't feel really hot and seemed to ride well. Here is my issue. The tire guy said he would run the tires at 50 PSI. Yet the tire says 80 PSI. I checked the DELNAT web site (they make the tire) and really couldn't find an inflation range. I have read suggestions from Bill and others about inflating them slightly less than rated during the hot months. But now I am confused. Should I run them at the suggested 50 or the rated 80 PSI. I was even thinking a compromise at Trailmanor's 65 PSI. Looking for some good advice on this. Heading up to Toledo, Ohio Saturday morning and don't want any problems.

Many thanks. Daveinfl

Redtail Cruiser · 06-19-2014, 03:44 PM

Dave, I've been running 60 PSI in my "D" load Maxxis and they stay cool to the touch. 65 Psi sounds right for the "E" load range. At 80 PSI you would vibrate every screw loose in your trailer, but at 50 PSI the tires might get pretty warm.

**ShrimpBurrito** · 06-19-2014, 05:07 PM

I run 65 psi in my load range E tires. When I first bought them 3-4 years ago, I ran them at 80 psi, and as Tim suggested above, it rattled alot of stuff loose. So after a few trips of that, I deflated to 65 and haven't had any problems since.

Dave

hillbillyhotel · 06-19-2014, 05:35 PM

ditto here, run at 65 psi ,
into our 2ed season on them, no trouble so far

scrubjaysnest · 06-20-2014, 07:59 AM

Started ours at 80 psi per maker and wmtire. No problems there; into our 2nd season on them and have settled at 70 psi based on over inflation indications. Again no problems.

Padgett · 06-20-2014, 09:41 AM

OK you do not have to use the maximum inflation. What you do need to us is an inflation appropriate to the use. In the upper ranges the inflation vs load is pretty linear so if you figure a 2720SL is about 4k running down the road and the tongue weight is 450 than the residual is 3550 adding a 15% shock factor and you are back to 4080 or 2040 per tire. If the tire is rated at 2830@ 80 psi then the theory says 57 psi so 60 is fine.

OTOH my 205x75R15 LRD are rated at 2150@65 psi so using the same method you get 61 psi or about 4 psi more than the 225s mainly from the lesser chamber volume.

All you really need to know without getting into complex math, standing wave effects, & tire engineering is that load is related to volume and psi. The tire size (205/75) relates to volume. The main thing is that higher "Load Ranges" for a given size add is more psi. Also radials have less drag (run cooler) than bias ply.

I use a similar method when racing in stock classes but figure the entire vehicle load is on the outside wheels in a hard corner (1+ gee) which produced some astounding pressures. All I can say is that when first using this method I began hitting inside pylons.

davlin · 06-20-2014, 01:31 PM

Daveinfl,

Like others, I run my load range E tires at 70 psi, which still exceeds the load rating that I need for my loaded 3124KS. I would think 50 psi might be a bit low, even for your 2619.

I'm most intrigued by your photo. Most trailer tire (ST) blow-outs (not caused by external puncture) are sidewall failures. This was clearly a tread failure, which could be caused by manufacturer's defect (many horror stories about Marathons) or excessive heat due to high ambient air temperature and high speed. Just out of curiosity, what speed do you drive with your TM?

Dave

daveinfl · 06-20-2014, 07:53 PM

Dave,

I have found my sweet spot to be 60 mph. That is where I get the best mileage with the trailer. I tend to run on Cruise Control on Interstates. At the time the tire tread blew off, I was on Cruise doing 60. It was very hot and we had just gone through Memphis where even the Interstate roads were very rough.

I believe I will probably bring the new tires up to 65 psi. I think that will keep me in the ball park. Thanks to all for your fast response.

daveinfl

Padgett · 06-20-2014, 09:24 PM

Just ran 70 miles at 65 mph on cruise @ 60 psi & OAT 90F Tread felt slightly warm, not hot. Did have tires balanced.

davlin · 06-21-2014, 01:43 PM

Quote:

Originally Posted by daveinfl

Dave,

I have found my sweet spot to be 60 mph. That is where I get the best mileage with the trailer. I tend to run on Cruise Control on Interstates. At the time the tire tread blew off, I was on Cruise doing 60. It was very hot and we had just gone through Memphis where even the Interstate roads were very rough.

I believe I will probably bring the new tires up to 65 psi. I think that will keep me in the ball park. Thanks to all for your fast response.

daveinfl

I think you'll be happy with that psi. And your running your "ST" tires well within the safe speeds for them, so I expect you just had a tire with a defect that was waiting for a bad piece of road and hot day. Doesn't sound like you did anything wrong. I've watched (and heard) of folks running those ST tires at 80+ mph, and IMHO, that's just asking for a failure.

Dave