tire failure

[thataway]

I have a single axle for the C Dory 22--I would prefer a tandem axle, but don't see spending the $$ to "upgrade". I have about 8,000 trouble free miles so far. The trailer is rated for " 4350lbs" with 15" rims at 65 PSI and ST225/75 x 15 load range D (my old tires were rated at about 2540 @ 60 PSI )

Today I put new tires all around (spare was brand new, 8 years old). The new tires are 225/75 x 15 Load range E--rated at 2830 lbs each tire, at 80 PSI! So you have to watch out--do you want to inflate a tire to 80 PSI that is on a rim rated at 65 PSI? For me the answer is no. So my carrying capacity is probably not really increased--but I do have a heavier wall tire--as noted this is a 10 ply rated, vs an 8 ply rated…

[colbysmith]

Hi Bob, what air pressure are you running in the tire then? I've always been told that with car tires, you run the recommended tire pressure from the owners manual, which is usually less than the tire max. On the other hand, I've been told with RV tires, which I'm not sure would include trailers, you run the max listed on the tire. Would be interesting to see any charts that provide a scale of pressure vs. weight. I came across this recently also with what pressure to run in my car tires with the additional tongue weight of the trailer. I got an interesting reply:

Subject: RE: FW: Tire info
From: Colin Przybyla The Tire Rack <colin@rerack.com>
Date: 7/16/2013 9:14 AM
To: "mcs2442@gmail.com" <mcs2442@gmail.com>
Hello
We don’t have a specific recommended inflation for the 2010 Toyota Highlander when towing. The
recommended inflation when towing should be obtained by Toyota, since they do validation testing with
a loaded trailer to determine the max towing capacity. You may need to contact Toyota directly if the
information is not in his owner’s manual, since the dealer will likely not know the recommended
inflation pressures when towing.
Your OE tire sizes are P-metric and achieve max load at 35 psi, so increasing inflation will not increase
load, but may provide less sway as the vehicle travels down the road. If you are using a standard load
Euro-Metric tire, the max load is achieved at 36 psi and Euro-Metric XL the max load is achieved at 41
psi, so increasing inflation above those levels will not increase the load capacity of the tires, but may
provide less sway as the vehicle travels down the road.
Best regards,
Colin Przybyla | Sales Specialist

I've always ran the tire sidewall shown max pressure in my trailer tires. Considering the side loads placed on tandems (or more) while turning, I'm not sure running them with any less is beneficial and may actually be disadvantageous. You do bring up a good point about wheel (rim) max pressures also. Anyone increasing to a higher load range tire, should insure the rest of the equipment can handle the load as well. My load range C tires, using 50psi, show a max weight rating of 1,760 lbs. On a tandem that's 3520 per side or 7040 for the boat and trailer. My C-22 and trailer weigh 5065 total, with 4660 of that on the axles. In my mind I have plenty of reserve weight capacity on my load range C tires when everything is working properly. With a blown tire I'm going to slow down and just limp along to a safe place to put the spare on. For tires that should be replaced every 4-5 years, I'm not sure I see the need to upgrade to a more expensive tire. Colby

[thataway]

Colby,
Excellent points. First, my local dealer told me they have a high demand for the 225/75 x 15, and the E range was only a few dollars more than the D range, so they carry the E range. I had checked on availability yesterday, and asked the dealer to have the newest tires available (they got early Dec 13 for me). Seemed reasonable.

In RV's we weigh each corner of the RV, and then inflate the tires according to the manufacture's charts. RV tires often are $500 to $650 each, so this is a significant purchase on the larger RV's. For example I am carrying 110 i my steer axle, and 100 in my duals. I am carrying about 36,000 lbs total.

For the trailer, I will carry at 65 lbs. It just so happens that Maxxis (the brand I purchased) has a load chart on the internet:

http://www.maxxis.com/trailer/trailer-tire-loadinflation-chart

At 65 lbs my capacity is 2540 lbs per tire, more than the "trailer" is rated for--but that is fine. It is also the load which the load range D tire is rated max. The prior tires were only inflated to 50 PSI (don't remember brand). which would be the 4350 lbs the trailer is rated for….and would be a load range C--a bit confusing, because the trailer tag says load range D at 4350 lbs. However, I suspect that different brands of tires are going to have slightly different capacity. That is true for RV tires, so probably true for trailer tires.

[colbysmith]

Wish more tire manufacturers had charts like that, easy to find!

[rogerbum]

Bob,

I'm not sure I've ever seen an inflation max rating for a rim. Is there something printed on most rims that specifies this?

[thataway]

Roger,
The RV rims are stamped on the outside of the rim. They are 22.5" tires, with aluminum wheels. (Edit--I looked at the RV rims, and they have a number of code letters, plus the max pressure of 125 PSI, and the tire width of 8.25")

I just looked at the trailer rims, and neither have any markings on them, but look to be the same manufacture (two different boat trailers). The C Dory Load Rite trailer on the sticker is embossed "15x6J rims at 65 PSI". I read that most rims have the pressure stamped on the inside. I did not confirm this when the tires were off today.

I have heard to rims splitting when too much pressure was applied in RV trailers.

[rogerbum]

[Sunbeam]

[Robert H. Wilkinson]

I don't know if they still use them , but years ago some trucks came with split rims. My 1977 Land cruiser had them. The bead on one side was removable - the tube and tire was installed then the metal ring was pried on and locked in a groove. A lot of accidents with these - tire shops were supposed to cage or chain them before inflating. I never saw one of these explode but the car cleanup guy at the dealership where I worked once tried to install a 16' tire on a 16.5' rim(havn't seen them for a long time either) - he had it installed and thought if he put enough air pressure in it he could stretch it that half inch. Don't know how much he had in it but everybody in the dealership knew when it exploded! He was knocked out, lost 2 fingers and had his arm broke in several places.

Compressed air can be a bomb - but I have not heard of a normal type rim exploding before.

I just bought new radials to replace the bias ply that came with my boat. The tread was very low after 3 years. Just went out to look at them - they are 225/75/15 load range D rated at 2540pds at 65pds.max - looked at the inside of the rim - it says rated for 2600pds. Couldn't find an air pressure limit marked on the rim. Am hoping the radials will last longer than the bias did.

Higher load range tires should last longer, but they will give a slightly rougher ride.

Regards, Rob

[colbysmith]

Sunbeam, I think the maximum tire pressure stated on the tire, is for the maximum load of the tire. I understand the email I copied in an earlier post of mine states that each auto manufacturer would have data for the maximum load they rated their vehicle at with a set tire. Ie, in my case regardless what the tire said, the 2010 Toyota Highlander when towing, the recommended rear tire pressure is 36. (I eventually found this in my owners manual...) I suspect this has more to do with the max rated load capacity of the vehicle, not the tire.

[thataway]

I suspect that there are a lot of factors in a car tire--including max load, ride, tire wear and fuel economy to name a few.

Good point about compressed air: for some reason the tire guys were having a problem getting one of the three tires to seat properly on the rims. They have an approximately 5 gallon air tank, which fits on the rim, is charged thru the compressor, and dumps the entire tank under the rim, into the tire space in a split second, to help seat the tire. When that discharged, and seated properly on the rim, there was a lot of force, and noise.

In my Yukon I run higher pressure in the rears especially when towing--because of the load in the vehicle as well as the better handling.

[journey on]

Bob, do you have a specific place you go to to get the tyre capacity vs pressure? I can't seem to find anything for trailer tyres.

Years ago a tyre rep pointed out that a tyre is like a spring. The more pressure you put in, the more the tread grows. His comment was to inflate the tyre to the load. I see this in the Toyota Camry, since the rear tyres are carrying a lot less weight than the front, and unless I run a lower pressure, the middle wears out quickly, before the side tread. I assume this is because it's carrying most of the load.

I know the load on the trailer tyres, since I weighed the trailer/boat/everything else and each tyre carries a lot less than it's capacity. If I can find a tyre capacity chart for a 225\75R 15E, I would be able to put the correct pressure in. I assume any chart for that size could be used.

So, Bob do you know where I can find such a chart?

Boris

[Will-C]

On our trailer an aluminum tandem axle with torsion springs we run 14" Carlisle radial load range c tires at 50 pounds cold. Our tire guy recommended the pressure which matches the cold inflation recommendations on the side of the tire. For me increasing the tires load range would not exactly change the trailers load rating. I would think that it would be more of a function of what the axles and springs were rated for would dictate the trailer load capacity. Our tires are rated for 1760 each so at 6000 pounds for the boat and trailer we are below the 7040 for which the tires are rated. We have about twenty thousand miles on the above tires and they have been good so far. We have traveled as much as 800 miles in a day in warmer weather towing the boat so if anything was weak I believe it would let go. I don't have a point and shoot thermometer but I lay my hand flat on all for tires every stop and that gives you a pretty good idea of what is going on. I take two fingers and touch the hubs and look to notice any one wheel running hotter Heavier tires add to the unsprung weight and I wonder if they do in fact run warmer? I would have liked to increase the diameter of my wheels but that would result in having to modify my fenders mounts braces etc. But in my thinking anyway increasing the wheel and tire diameter has got to help. Our truck recommends the front axle tires be at 60 psi cold and the rear axle tires run at 70 psi cold. I wonder if trailers with leaf springs which seem to ride a little rougher that torsion springs could in fact increase dynamic loads placed on the tires while dealing with road irregularities. Pa. roads are nothing to brag about.
D.D.

[thataway]

Boris, the link I posted above:
http://www.maxxis.com/trailer/trailer-tire-loadinflation-chart
Does have the 225/75-15E (which is what I have) at 80 PSI.

Boris, if the middle is wearing excessively, this usually means that the tire is over inflated. Under inflation, the edges tend to wear more.

Dave, I agree that just having higher load range tires, does not increase the trailer capacity--but since the tires is often the weak linK (and part of that is the road condition)--it is of value to to have the larger tires.

It is unusual for an axle or spring/frame to fail, but they certainly can. Looking at my trailer--the weakest point now is the axle. The trailer frame is certainly beefy enough.

The "pro" RVers--and one of the Monaco moderator is an automotive engineer who was a Federal DOT regulator--are very careful about matching the tires, wheels, bearings, axle's springs, air bags etc all together so the are both save and give a good ride. It is re-assuring to have someone of that caliber commenting on what is correct.

[thataway]

One subject we seem to have avoided for some reason, is that of tire temperature and pressure sensors. Almost all new cars have them. Most RV's have them, and there are plenty of "add on" systems: Such as the
http://www.tiresafeguard.com. My RV has an older unit which you cannot replace the batteries in--and I am going to upgrade to one of their units. I'll just throw it in the truck for monitoring the C Dory trailer tires.

I will still stop every two hours to check the hubs, with the IR thermometer.