Why tires fail

Tireman9 · 02-17-2018, 09:20 PM

Tires fail from two basic causes.

Low air pressure
and/or
Long-term degradation of the rubber usually from excess heat.

Low pressure (active leak from puncture or loose valve stem or valve core are most common reasons) can lead to a Sidewall Flex failure or more commonly called a "Blowout". The sidewall cord can melt (polyester) or fatigue (steel). Many TT owners fail to realize that they will never "feel" the results of a tire losing air till it is too late and they are surprised when the sidewall lets go. The rapid air loss "bang" even when the tire only has about 10 to 20 psi in it, is a big surprise IF they even hear it. A TPMS can provide warning of air loss so is good insurance and can easily pay for itself.

The long-term degradation of the rubber at the edges of the belts can lead to a belt and/or tread separation. Even if the tire keeps its air you can have this type of failure so a TPMS will not provide a warning. This degradation comes with age as rubber is always losing flexibility. Just think of those rubber bands you found in the back of the desk drawer. Even in cool and dark they got brittle. However, running at or near or above the load capacity of a tire will result in increased heat generation. Increased heat actually can accelerate the aging process with a doubling of the rate each increase on 18F. Running a margin of at least 15% between capacity and the measured load is a good first step. Running at a higher speed will also generate excess heat.

Realizing that over half of the RVs on the road has one or more tire in overload is one main contributor to the high tire failure rate. Simply thinking that a tire will fail because the tire plant building is painted blue rather than green is not logical.

Buying the lowest cost "no-name" tires is IMO a major contributor to poor results. If the main objective is the lowest cost tire why would anyone be surprised with short tire life?
Just paying more, however, is no guarantee of better quality. I believe the best tool available is comparing Warranty and service support.

Can you get multi-year warranty on the tires? Is it possible to get Road Hazard coverage? Is there a nationwide network of dealers who stock the brand you are considering?

**fairweatherfisherman** · 02-18-2018, 05:43 AM

Very interesting. Thanks for the post.

Padgett · 02-21-2018, 11:34 AM

+1 on major causes. Must admit I look more at Overlay or Cap, and Load Range with reviews a lower incidence. Do look at who made the tire and where (in the DOT code) more than name on sidewall. Also I develop a set of criteria and only when that is satisfied do I look at price but it is a factor.

Finally as part of the purchase I have spin balanced immediately. Finally stick to a 65 mph limit for ST tires and have a TPMS system.

tentcamper · 02-21-2018, 07:14 PM

Is there any benefit of buying a higher rated tire such as a D or E and than inflating to your load using the Load Inflation PSI Chart. The PSI might fall into or below the max load PSI of lower rated tire such as a C or D?

Padgett · 02-21-2018, 08:43 PM

In general the higher rated tires have a stronger construction to handle the higher inflation pressure. Load Rating used to be called "Ply Rating" and a 6PR was LRC, 8PR LRD, 10PR-LRE. See here for a complete description.

Tireman9 · 02-22-2018, 09:00 AM

Quote:

Originally Posted by tentcamper

Is there any benefit of buying a higher rated tire such as a D or E and than inflating to your load using the Load Inflation PSI Chart. The PSI might fall into or below the max load PSI of lower rated tire such as a C or D?

No. You only get the benefit of increased load capacity with an increase in inflation. The fact that all tires from all companies use a "Load & Inflation" chart is proof of that engineering fact.

Tireman9 · 02-22-2018, 09:04 AM

Quote:

Originally Posted by Padgett

In general the higher rated tires have a stronger construction to handle the higher inflation pressure. Load Rating used to be called "Ply Rating" and a 6PR was LRC, 8PR LRD, 10PR-LRE. See here for a complete description.

Sort of but sometimes the increase in "Load Range" can be made with only a change in the bead wire. This is the wire that keeps the tire mounted on the wheel. Other times there may be a small increase in the number of strands of steel in the belt but remember that we may be talking about going from 20 strands per inch to 24 strands per inch. This is many times done only to allow the higher rated tire to pass a single DOT test called "Plunger" where a 3/4" diameter steel rod is forced through the center of the tread.

I was confronted with both these cases in my career.

flipflop · 02-23-2018, 07:50 AM

Aerospace 303 on the tire sidewalls keeps them healthy.

Tireman9 · 02-24-2018, 08:56 AM

Quote:

Originally Posted by flipflop

Aerospace 303 on the tire sidewalls keeps them healthy.

Yup it keeps them looking good and claims to protect from Ozone and UV, although I have never seen independent test data.

But it is IMO more important to keep the tire structure, especially the belts) i good condition by not overheating or over stressing them.

Heat and stress comes from high speed, overload, or low inflation all of which are in the control of the user.

eddugo · 03-01-2018, 04:59 AM

What I have done to try to prevent blowouts is add the lift kit so I can use 225/75R15 Maxxis 8008 tires. This gives me 5080 load capacity. my TM weighs, depending on the trip right at 3,000 pounds, about 60% of tire capacity. Pressure kept at 65 psi and speed at 60 mph will hopefully keep me blowout free. I keep the tires fully inflated and parked on pressure treated wood when not traveling. I think I'm on the right track from all the research I have done.