tireman9

You didn't mention the Load Range of your current tires or if you know the real load on each corner of the RV. This information will help us provide informed advice as there may or may not be a need to address the Load Range as well as size. Looking forward to learning more about your rig.

Basically if you can see any cord or steel at the bottom of a cut or snag you should be replacing the tire. If you use a flat blade screw driver to pry the cut open and see anything that looks like cord you should replace the tire.

Don I note that the XZA2 Energy has deeper tread. 1/32 isn't a lot but it will probably affect fuel economy a bit with the deeper tread tire being worse. (Unless Michelin wants to state otherwise in writing). I wouldn't get too hung up of "Regional" service as most truck tires seem to use "Long Haul" or "Regional" or "local delivery" to describe their tires expected usage. I would generally not consider "local delivery" for RV use unless the tire MFH identified the tire as approved for RV usage. "Long Haul" implied high mileage long wear and I see no reason to pay for tread you are not going to use. Other than than that either tire is probably OK for your application.

Paul, The reason for wanting the same tire(s) on each end of an axle is to try and keep the vehicle response to steering & braking input the same so the vehicle turns Right & Left the same and under braking doesn't dive right or left. Obviously the fronts are more important than dual rears for these characteristics. When we move to the rear of an RV we have duals to consider. Unlike cars, handling of dual rears is less important IMO than ensuring we don't have a tire failure due to unbalanced loading. Here we need to look first at the pair of tires on one end. Of primary importance is matching the rolling radius of the two tires that work together to hold up that end of the axle. Now accurately measuring rolling radius is a challenge if you don't have a tire measurement lab available. However you can confirm that the tires are "close enough" by measuring the inflated Circumference. If the OC is within 3/4" you are good to go. If the difference is greater than 3/4" you need to find a better match. When I rotated the tires on my Class-C I ended up matching two pair for the duals based on OC measurement. Each pair matched at about 1/2" OC variation. The remaining two tires went on the front. Now I admit that all my tires are same brand & size and the wear on the two fronts was different by about 3/32" of tread wear and one was new so the OC was different based on tire growth. I have not noted a difference in steering response but have (luckily) not had to do any emergency braking but feel the vehicle response will be acceptable. I think that as long as you #1 match the fronts by brand, design and similar tread depth and #2 ensure you match each pair of duals by brand, design and OC you should be OK to go. Hope this clears up any confusion.

"truck tires have more sidewall ply's than the RV tires" I think you might want to read the material list on your tire sidewall. Most 22.5 tires have one body ply of steel in the sidewall and three of four layers of steel belts under the tread. I note that the Yokahama 245/75R22.5 is considered as replacement (equivalent) for Michelin XZA ,Goodyear G169, Bridgestone R250. All of which I believe have one body ply. (could not quickly find this info for all these tires) as that is normal HD tire construction.

Brett is correct in his answers. There are TWO potential Safety issues. One is a potential of a rear tire failure due to overload. The other is potential for unexpected handling in emergency move from mis-matched fronts. The only way to avoid the front tire issue is to have the identical size, Load Range, Brand and design on both fronts with similar levels of wear. For matching duals on one side, the tires need to be the identical size, Load Range, Brand and design and in my opinion must match unloaded, measured OC within 3/4". A difference greater than 3/4" will result in the larger tire being forced to carry a larger % of the load of that side which could lead to premature failure. Here is a 1 min video on this topic. Matching side to side of the rears is less important than for the fronts but each side of the rear needs two tires that match. As far a carrying a tire for a spair, check out my 1 min video on that topic.

If you are getting new stems, the truck center that will be installing them should have a selection on hand.

If you Google TPMS or Tire Pressure Monitor System you will find numerous systems. I would suggest you make your own comparison sheet and check each system. Initial cost for system with enough sensors for your RV and toad. Length of warranty. Cost of ownership for 5 years and assume one change of batteries on all the sensors. Be sure to note if the batteries can be changed by you or if you must replace the sensor when the battery goes dead. Cost to install if the sensor mounts to the wheel (similar to the sensor on your car). If sensor just screws on your current valve this cost is $0 With a 35' MH I assume you have bolt in valve stems. For some owners of smaller RVs they might find they have rubber stems and it is recommended that these be replaced with metal stems. I have 15 posts with the key word TPMS. I am sure some will answer other questions you might have.

In real life you are not presented with two pictures of the same tire on the same piece of ground. I will give you that on gravel might make it more difficult but some claim to remember what a properly inflated tire "looks" like when they do a simple visual inspection during a P break. I noted you did not identify which view had less air and if the tire was more than 20% low.

If you are going to the Perry GA Convention March 17-20 2014 come to my tire seminar for lots more info from a Tire Engineer.

In controlled testing of Professional drivers the best they can do is spot a tire that is only 20 psi low. You have been lucky. Too often people think that because they checked their tires 50 miles or 2 days or a week earlier it is impossible to get a flat due to cut, puncture or leaking valve. This person insisted that they had used a gauge 50 miles earlier. But here I proved they had suffered an air leak. In reality you can't tell the low inflation that is doing damage to the tire structure even when presented with the artificial comparison never available in real life. If you think you have a calibrated eyeball what do you think the pressure is on this tire? and how much air here Don't forget a loss of 20% is considered Flat for warranty purposes. Looking forward to the answers. Will check in a few days.

Did a post on my blog specifically on Air Compressors. Bottom Line is that with a little planning even full timer may be able to avoid needing to buy and carry a compressor. Previously offered a suggestion on how to "Top Off" your inflation when you have to drive a couple miles to get to a HD compressor. RE Pressure Gauge Accuracy. Have a new blog post that will go "Live" later this week with specific suggestions on gauges. Also am planning a post on weight & tire inflation and the difference between "measurable" and "meaningful" when it comes to tire loads & inflation.

OK Sorry for slow reply. Found my 1977 Tire & Rim Book and it shows for an 8-17.5LT OD 31.02 Section Width 7.85" on a 5.25 wide rim You didn't say what Load Range you have or need but I found LR-C 45psi 1820# dual 2075# single LR-D 60 psi 2155# dual 2455# single LR-E 2460# dual 2795 single. I can help you look for a modern size and Load range but really need to know your current tire loading (or at least the axle loads F and Rear) If you want you can drop me email so we can work this out Tireman9@gmail.com

That size was declared "obsolete" in 1997. I am on vacation now so do not have acess to my old data books but if you wait till the weekend I can look up the data and give you the specs so you can find an appropriate and more available tire.

Your LT225/75R16 LR-E tires probably show 2,680# @ 80 psi single and 2,470# @ 80 dual which would give you 5,360# capacity if you had perfect 50/50 side to side load balance on the front and 9,880@ for the rear axle. Once you know your real corner laods you need to be sure to select the inflation that would carry the heavier side as your MINIMUM cold inflation, but I would suggest at least +5 to +10 over that as long as you do not exceed 80. Again knowing the actual tire loads will help us give you the answers you are looking for. Before you buy new tires get your actual tire loads.

I think this post will answer your questions on "Ply Rating" vs "Load Range". Read the information on the sidewall of your tires. You should see the words "Load Range" followed by a "D" or "E" most likely. The "2 polyester, 2 steel, and 2 nylon" are just telling you the materials in the tire not the strength of each material. Load Range is what you are looking for. The Mfg sticker or "Tire Placard" is based on an estimate of what your actual load will be on the tires. It would help if you at least got the individual axle loads. Even better learn the individual tire loads. This post covers why individual weights are important. There is a worksheet with instructions you can download here.

I think running an RV without a TPMS would be like running without an oil pressure gauge or without engine temp gauge or without voltmeter.

I believe in this case Goodyear is talking about Ozone & UV damage. Don't know how they would add chemicals to a tire sidewall that would "protect" it from heat damage. Remember that UV and Ozone can attack the surface of a tire, but heat can attack the internal structure of your tires.

Something to consider if you have a hard to find size. You might consider keeping an old worn tire, unmounted, in a storage bay if you have one large enough. You can still pack a lot of "stuff" inside the tire and if you ever have a tire failure this spare would give you something that would at least get you off the road while you wait for a new tire. Here is my video on the topic.

If you bought a Road Hazard warranty should be no problem. Otherwise I have to wonder why Michelin should be responsible for a tire that suffered an air loss due to puncture, cut or valve leak? Simply Google Radial tire zipper failure and you will find numerous examples

Don't forget to have the valves, or at least the rubber grommets and O-rings replaced whenever you have a new tire installed. Rubber parts of valves age just like tires do. A good tire dealer that services trucks all the time should do the job properly and ensure the valve is installed with the correct torque.

For those that may not know what a "zipper" failure is, here is an example. This is what happens with a steel body tire, while Nylon or Polyester body ply melts, steel fatigues. Think of what happens when you bend a steel paperclip back and forth.

If you have the air pressure monitors in all your tires I think you have done a reasonable job. If you already have the "crossfire system" I guess this would mean you could save some $ and just get a 4 sensor TPMS. I do understand the concerns some have on hoses. This is my set-up Note how I have the ends of the hose BOLTED firmly down. I think that it is possible that many of the hose failures are due to inadiquate mounting of the hose so it can move which could fail the hose and/or valve.

I have two YouTube videos just on spare tires Should you carry a spare http://youtu.be/mRy9BYZL5RQ What you probably don't know about your spare http://youtu.be/WMxBIKl_wn8

Danshan432 I understand how easy it is to get confused about Nitrogen. One one hand you have the proponents using some of the data to support their position that N2 is just short of magic. I and some others will agree that there are some theoretical and even some real advantages. The question is: Do the advantages justify the cost? and If the advantages are real, what is the real cost of trying to maintain 95% N2 rather than 79% N2 in your tires? RE not using N2 in old tires. I would really like to see that original message. As a tire engineer, I can not think of any reason for this to be a concern. Also have to wonder what is meant by "old". Do they mean tires that are 7 to 10 years old? or are they talking about tires you might see in an auto museum that are 30 to 70 years old? You are correct about most "shop air" not being dry. We are talking about how wet or how dry. I doubt that even the dryers used in auto paint shops is as dry as what comes out of 2,000 psi tank. Back in June 2012 I provided a link on how to make your own air dryer that I believe will provide almost all the benefits you are looking for when it comes to moisture at a fraction of the cost of N2. RE tie problems. First there is no reason for the inflation gas to affect the rate of punctures so that is a red herring. I notice you didn't mention the number of punctures out of the 35. My biggest concern with these kinds of "studies" is that they probably did not have a tire forensic engineer examine all the failed tires to learn the real reason for the "problem". One possible explanation is that when they switched to N2 they also changed their tire inspection and maintenance program. RE wheels. Thermal expansion of steel or aluminum will not be affected by the gas used to inflate the tires period. Hope this helps. If you still have questions please go back and read my other posts in this thread and then follow the links in my posts. Roger