tireman9

"New" age can be a problem or not. This isn't an easy answer as some new tires are stored in "better' conditions than others. Ideal storage would be indoors in relatively cool location. I have seen some tires at local gas station on mobile racks that are wheeled outside into the sun. Certainly not "better". Another thing to consider is when the warranty clock starts ticking. Some companies start the clock when tires are applied. In those cases you need to be sure the full DOT is recorded on sales receipt and that you keep the receipt and warranty info with other important documents. If your "new" tires are from a company with this policy you should have no problem. Other companies use the DOT date. In that case I would prefer 6 months or newer if possible. You might try and negotiate a discount of a few $ on the older tire Another thing to consider is how long you plan on keeping the tires and how you care for your tires. If you always cover them with a white cover whenever parked more than a couple days then you are following a good practice.

In my blog I showed the small air dryer I made out of parts from local auto parts store.

Ride is pretty subjective. While I have never personally done a comparison on 22.5" tires I have done many scientific comparisons on Passenger and Light Truck sizes. By scientific I mean back to back within the hour evaluation on the same roadway of new tire from tire company A vs new tire from tire company . We would run with no radio, A/C off and windows closed to cut down on distracting noise to do the comparison on the exact vehicle the tires were to be used on. This meant that many times we were using prototype vehicles when designing tires for new vehicles. We would NEVER use a Ford car to evaluate tires for Chevy or vs-a-versa as different vehicle manufacturers had different approaches to suspension, chassis and seat design. I specifically even remember when I had a special opportunity to do a "ride-along" when a set of wheels was being evaluated. In this case we ran the test route on one set of tires & wheels (cast aluminum) then the car came in and the wheels were changed with the tires being swapped out onto the 2nd set of wheels (also cast aluminum) in the same position so any difference in specific tires would not influence the results. I was amazed that I could feel the difference after less than a mile. All this is to point out that a difference in tires that one person may feel is not always a good predictor of what someone else may feel. This is especially true when comparing new tires with old worn tires. It is known that just a difference in tread depth can have a significant affect on ride with deeper tread being better. It entirely possible that the difference some feel is just due to tread depth along with the potential for personal expectations of what one brand can deliver vs another brand which can mislead or add to the difference between new vs 7 year old tires.

Here is an outside view on "Rallys" I read recently.

RE no seminars. My 4 Genealogy seminars are of general interest. The demographics of those that own RV ( MH or Towable) are similar. In my 2 seminars on tires I will add a slide at Indy and at Syracuse for the special inflation info unique to trailer owners. Not sure what else I can do to make more folks welcome.

x2 to comments from Brett, Bill and Carl.

What does the written warranty say? Some companies start the clock on date of application. Some on DOT. Having the dated receipt and written warranty down the road could be worth $hundreds so those are definitely valuable documents. You should be sure the clock on your "new" tires didn't start till the date they were applied.

When I was in OR before FMCA convention in Redmond I used one of the state scales after hours. The one I found had a wide open space around the platform. While things were not perfectly level it was reasonably flat and if the numbers had much different than my prior readings I could have run in both directions and with some math done an average. There was no rush as I was on a state road with not too much traffic.

Yes older is more likely but the reality is that if a specific date is given and a tire fails before that date the tire company gets sued. Also if a tire runs past that data then the tire company will be accused of cutting the time in an effort to sell more tires. The general guideline is to not run any tire that is older than 10 years old. There are some applications such as on multi-axle trailers 3 to 5 years is the normal max. Which of you has ever had a jug of milk go bad before the "expiration date? Who has had the milk still good days after that date. The issue is that we are dealing with organic material which can have numerous variables. RE DOT date. If you are still having problems get with me in Indy in July or Syracuse in Aug. Side note everyone should learn the full DOT serial of all their tires and write that info down and keep it with other important documents That way if there is a recall you don't have to go read your tires but just review your documents. I have suggested that if you aren't comfortable getting down and trying to find the DOT you find a teenager, give them a flash light and maybe an inspection mirror and have them read the serial to you. It's probably worth a few bucks. You might also read my blog post of DOT date code.

"Dry Rot" is a misnomer for cracking observed on tires, usually more observable on the sidewall. Rubber simply does not rot like an old tomato. Tire age in itself is not a serious concern but it can be part of a diagnosis or predictor. What is of concern is the elasticity, flexibility of the rubber at the belt edges and the adhesion of rubber to the steel in the belts and body cord. The problem is that it is impossible to know for certain, these conditions without doing what is known as a "cut tire examination". This is when tire engineers use power band saws and large cutting equipment (visualize a 12' tall guillotine with a 12" wide 1" thick blade sharp enough to cut paper, driven by a hydraulic cylinder with a few thousand pounds force pushing on the blade) to slice and dice a tire so the above characteristics can be accurately evaluated. In my career I conducted or was involved in many thousands such examinations. We would correlate the external condition of the tire before it was cut with the actual condition of the internal components. While one can never be 100% certain or accurate of a prediction, with thousands of such examinations under our belt we could be pretty confident that our appraisal would be reasonably accurate. Given that you would not want to destroy your tire trying to learn it's internal condition what is done is to use an externally visible condition of degraded external rubber i.e. cracking as a rough predictor of the internal condition. In general the more external cracking the more likely it is that the internal rubber could fail and tear due to a loss of elasticity. However external condition is not absolute as it is sometimes possible to have the external condition be worse than "nominal" if solvents were used to clean the tire or there was excessive exposure to sunlight. This can be observed by comparing tires that spend most of the time in southern states with one side of the RV facing South. I had a situation where the gel coat of the fiberglass side of my RV itself suffered significant cracking from UV exposure. There are other tools such as X-Ray that can identify if there is already a separation of the internal components which is used by retread shops but it would cost you significant time and money to dismount your tires, have them inspected and then decide if they go back on the RV or were scrapped. It could approach the cost of a new tire for the handling and process plus you would be with out tires for a few days to complete the inspection. So this is why we generally use sidewall cracking as an approximate predictor along with the tire age and sometimes a free spin inspection to help identify tires with a suspected internal separation before the tire comes apart. So we need to all understand that cracking is a bit like taking your temperature when you feel ill. An temperature elevated by a few degrees in itself is not going to cause "failure" or death but it is a symptom that can be used along with other symptoms to help your doctor diagnose your internal condition. Is the doctor 100% accurate? No, but with experience and training they can present diagnosis that are probably correct or at least very close. So maybe you can now understand why there is no absolute predictor of "end of life" for a tire based solely on calendar age. We need to use a number of different observations to reach an opinion that has a high probability of being correct.

Yup That's essentially what I posted Feb 2015

Carl, I suggest people select a CIP to be +10% of the minimum needed to support the measured load. I hope that when you discover your tires are "5 to 7 psi low" you are still above the minimum required to support the load. IMO any level below the minimum needed to support the load is not a good thing. If your minimum inflation needed was 90. Your CIP should be 99 but you are discovering your morning inflation is 92 to 94. All that means is you are not running a +10% margin to address side wind, cornering etc.

Here is a post from my blog in March 2013 for those that haven't scanned the various topics. "Hopefully all the readers of this blog understand the importance of having the correct inflation pressure in ALL their tires. Be they on a 45' DP or your toad, a tow dolly, regular passenger car or anything in between. The question is how do you get a few more psi of air for your tires when you check in the morning but aren't parked next to a supply of high pressure air? There are a number of different situations and I can't possibly address them all here, but I think you can review these suggestions and find a plan that will work for your situation. I do need to separate out the few folks that discover they have a flat tire or one that has lost more than 20% of the minimum required pressure. NOTE: Tires that have lost 20% of their air are considered "flat" by the tire industry. You have a problem. Maybe a puncture or a failed valve or a tire that has been damaged. You should not drive on your flat tire. You need to change it if you have a spare and the proper tools and experience to do the job safely, or have it changed by a tire service truck and technician. Now the rest of you who just need a few psi to get back to your goal inflation that provides the inflation needed to carry the load plus a few psi "cushion", there is a way to handle your situation. The options depend on how much air pressure you need. If you need 80 psi or less one option is to carry a small "tankless" or "pancake" compressor rated at 100 psi and 1 or 2 Cubic Feet per minute (CFM). These are available for $20 to $60 at discount tool supply companies or auto parts stores. Some are 120V and some are 12v and can run off your battery or on-board generator. Just be sure you have enough extension cord or air host to get to all your tires. NOTE You will have a tough time ever inflating a tire to the pressure the compressor is "rated" for so don't buy a 100 psi compressor is you need 100 psi. If you have a larger rig like a Class-A, you probably need 90 to 120 psi and a compressor rated at 125 to 150 psi and 2 CFM or higher. If you have air brakes you may have enough on-board capacity and just need the appropriate fittings and host. There are small compressors on sale at less than $100 that claim to be capable of 125 psi. One other option for those only a few psi low. Drive to the nearest service station at slightly reduced speed (10 mph under the speed limit would be max) and follow these instructions on how to inflate a hot tire. 1. Record your cold inflation. 2. Calculate how many psi each tire would need to reach your goal cold inflation. 3. Drive at reduced speed, hopefully no more than 10 miles, to the service station with air available. You might want to call ahead to be sure they have enough space or long enough hose to reach your rig. Not all service stations can accommodate a Class-A with a toad. 4. Measure your now warm inflation pressure 5. Add the psi needed from step #2 above plus 3psi to learn your temporary "warm" tire inflation 6. Inflate your warm tires to the temporary goal inflation calculated in step 5. 7. Confirm you have the needed inflation the next morning after the tires are at ambient temperature and adjust accordingly. If you follow these steps I think you will find that your tires have the proper inflation or 1 or 2 psi more so you can set the inflation at your exact goal cold inflation using your digital gauge. If you have any concerns then have a service truck come out to top off your tires. Remember DO NOT DRIVE on any tire that has lost 20% or more of its air"

If you cannot get individual "corner" weights as you can at large FMCA Conventions from RVSEF and other companies the next best thing to do is to get axle weights which is an easy process at truck-stop scales such as CAAT scales and similar. I believe that people should NOT simply divide by 2 and assume each end of an axle carries 50% of the axle total. A reasonable and conservative approach is to assume the heavy end has 52% of the measured load. Using that figure you can then use the tables to learn the suggested MINIMUM inflation needed. I also suggest that an additional margin of 10% of the minimum inflation be added to help establish the morning CIP. Set your TPMS warning level to warn at the MINIMUM number of psi and just review your CIP reading from your TPMS each morning and as long as you are 5% or more above your minimum you should be good to go. When you see you are down to only 5% margin then you can plan on adding a few psi at the next fuel stop.

While my Chevy gas 6.0L may not face the same issues as a 45' DP I have use brake fluid test strips. Brake fluid is a real safety issue for those of us who do not have air brakes. Test strips are relatively inexpensive (less than $10 for two) and available on-line and at many auto parts stores.

I thought posting this example might help those with the recurring question of "How much air should I use?" +++++++ I received this question. "I am a newbie. Just 5 weeks with my 2017 Bay Star 3113. I need some help understanding just what would be the correct or appropriate tire pressure on my coach. When loaded with my wife, dog and self, partial food and clothing, tools, chairs, BBQ ladders, 2/3 water, full gas and propane and misc stuff I got the following from the CAT scales: Front axle - 7,300. Rear axle - 13,260. Here is my dilemma: The dealer delivered the coach with about 85 lbs. per wheel cold, but when I use the Michelin Tire pressure chart for my 235/80R 22.5 XRE tires should be just 75 lbs! I am concerned that they will be "underinflated" and could build up excess heat. Should I keep the 85 lbs or lower the pressures?" ============== My reply: Welcome to RV fun. For all things tires (except buying) I obviously suggest you check my blog. I don't expect folks to remember everything but if you spend a few minutes checking it out, you can learn how to use the "Label List" on the left to find a post of the topic of interest. There is also a search box in upper left. Now to your specific question. 1. We want to know the heaviest load on your tires and since few RVs are perfectly balanced side to side for weight we ideally want to know the "4 corner weight" to learn the heavier end for each axle. lacking knowing that number IMO we can do a rough calculation by using 53% of the axle scale weight for the RV when it was fully loaded (the expected heaviest it will ever be). 2. 53% of your front would be 3,870# and rear would be 7,030# or 3,515 on each dual. 3. Looking at the Michelin load tables we find for your size at 85 psi can support 3,975 for single (front position) and 80 psi supports 7,050# for two tires in dual position. Yes we always round up. 4. Based on the above your MINIMUM inflation would be 85/80 This is the number I would use for the low pressure warning numbers on your TPMS. 5. I recommend adding 10% and again rounding up that means 93/88 psi for your Cold Inflation Pressure or CIP In your case given the close numbers for the front load I would be comfortable using 90 psi all around as a single number is easier to remember. This 10% gives you a nice cushion so you do not have to chase your tire pressure around whenever the temperature rises or falls. You could even get down to 85psi before needing to "top off" the tire pressure again. 6 All tires on an axle should be inflated to the same level for improved handling and response in an emergency situation. 7. I would set the TPMS High Pressure warning to 110 to 115 psi and your high temperature warning level to 160F. 8 Remember CIP means when tires are at ambient temperature and have not been in direct sunlight or driven on for at least two hours. Finally, In your case you are close to some numbers when we round so if your RV is more balanced than my suggested 47/53% you may be able to lower my suggested inflations by 5 psi but only when you confirm your heavier end is less than 53% of the total. +++++++++++++++++++++++++++++++ PS The above post will be on my blog in a few weeks. You folks just got the "Advanced notice".

If the chart starts at 85 that would be the MINIMUM. I still would add 10% for a nice margin. Note you got the load increase not from the Load Range change but from the size change.

Two things to consider. If you use anything in the tire that is dry (beads, sand, powder) you MUST install the correct valve stems with the appropriate filter. Also you need to read the fine print in your tire company warranty. Some say the use of anything inside the tire may void the warranty. Just be sure that whoever is installing the balance stuff offers appropriate warranty coverage.

No matter what your system is you should be running a TPMS. Leaks can occur for a variety of reasons. With sufficient advance notice it is possible to stop and take corrective action before the tire is damaged due to running with low pressure. TPMS are good for many years of service with only the few $ to cover sensor battery replacement every few years. You only need to avoid one tire failure to cover the cost of the entire TPMS system. Good investment IMO

RE hoses. There are two types. "Airless" and pressurized. As I understand the difference (haven't bought a set to cut up and examine) Airless have a special long valve core that is essentially a pin that runs the length of the hose and actuates the valve core in the valve stem. This type may sometimes cause problems if theTPMS doesn't depress the rod/pin enough to open the valve core on the wheel end. Pressurized have a regular valve core at the outer end that is actuated by the TPMS itself. This is the type I run.

IMO many times the failure of a part or accessory can be traced to faulty installation of the part in the first place. For some reason the concept of not having a hose rub against a wheel or hub cap and to ensure the hose is not loose or over-tight seems to be beyond tha ability of some tech people. Of course it is also entirely possible that training for anything related to tires is at the bottom of the list of things to expend some time and effort on. I have over 75k miles & 9 years on 2 sets of hose extensions with no failures but maybe I'm just lucky.

At 13 + years you might want to check all rubber components, Brake lines, fuel, coolant hoses, suspension bushings.anything rubber will age and may loose the ability to do what it was designed to do. Some more critical than others

What ever you get, you should be sure to run TPMS on metal bolt in valve stems. Stray stones can puncture or cut and result in a slow leak.

I have a number of posts just on Duals. on my blog. Dealing with duals is something few people ever have to deal with till they get a large RV. Matching duals is critical and if not done correctly can result in shorter life or even a failure. Please pay special attention to the information on proper matching. As previously mentioned in this thread. Tires of different design and from different manufacturers can deflect differently even if the measured OC is the same. That is why you should not mix brands in a pair of duals. After reviewing the information if you still have questions you can drop me an email.

I agree with Bill Adams that the best is to know the individual weights on each end of each axle because few RVs are balanced 50/50 side to side. An option which will cover most RVs is to assume one end has about 53% of the axle total. Once you get on a truck scale (most large truck stops have them) get the weight for each axle. You can ask in the office and they will be happy to help. With the weigh slip that shows both axle weights the next step is to look up a Load & Inflation table. Most tires follow the same table but you can check HERE Using the 53% figure you will know the Minimum Inflation. I suggest you add 10% to the minimum inflation to give you a cushion. You will see your morning inflations go up and down a bit with morning temperature. Check out my blog if you want to learn more