tireman9

Ah the $64 thousand question. Just as easy to answer "What is the best RV" or what is the "Best hamburg". Some will swear by Brand A while others swear at Brand A. I did a post on things to consider when selecting a brand of tires. Take a look and I think it might help you find the best for you. Similar answer on best campground club/association to belong to. Doesn't do much good to select a club/association if they don't have locations where you plan to travel or don't offer the features you want. I would suggest to first identify the features you want (swimming pool or river or lake or hiking or kids playground or mountain trails etc) then lay out a couple of possible camping adventures and see who offers campgrounds where you intend to travel.

You might want to follow the logic in my post on Tire Pressure. i.e. add 5% to tire load to accomodate the probable unbalance, Consult the tables and do the math then add 10% to avoid daily pressure changes as you travel. Remember the Goodyear & Bridgestone Firestone charts show individual tire loads not axle as in Michelin tables. Basically all tire companies and regulatory agencies worldwide follow publishes industry standards with only minimal deviations on some individual tires by some companies. If your tire company doesn't offer its own tables showing some exception then a reasonable approach would be to follow the major tire companies. If your load at inflation molded in the tires match the numbers in a table then you can be pretty confident the rest of the values will follow. I have never seen an instance where the maximums match but the lower published values do not match. I also strongly suggest you get a TPMS as even checking the tire pressure every morning does not mean you did not pick up a nail as you drove out of the campground.

I agree that the Michelin tables can be a bit confusing as they are different than most other tables in that they show the load for the entire axle rather than the individual tire(s). But here is how I would work through the math (until you get RVSEF or similar company to give you the individual weights): 1. You need to add 5% to the measured load as you really are not 50/50 side to side balanced. Most rigs are within 5% but some can be 1,000# or more out of balance. So you should think Front axle 12,264 Rear Duals 17,997 Tag 6,090# 2. Looking at the Michelin tables for your LR-H tire (careful as they show different for LR_G) we find: Fronts (single) axle rating of 12,380# at 100 psi cold Rear (dual) axle rating of 18,160# at 85 psi cold Tag (single) axle rating of 6,090# at 75 3. The above pressures should be considered your MINIMUMS but I suggest all RV motorhome users run an extra 10% so you don't have to be chasing inflation if you run into a cold front and the pressure drops of if you have a really big Walmart shopping trip. So you should inflate your tires to at least 110, 94 round to 95, and 83 round to 85 for the tag. 4. Be sure to have a good digital gauge and stop at a Michelin tire dealer and check your gauge against their master gauge. (If they don't have a master gauge then find another dealer) Your gauge should be +/- 2% or less and most digitals are +/- 1%. NOTE When I do gauge calibration checks at the rallies I attend I find more than 10% of the gauges are off by more than 10% so they usually end up in the trash. If you want to learn more about tires and can't make the FMCA convention in Indy you might want to read my blog from the beginning.

While finding a location may be easier for some than others, it is important to do the math correctly. RVSEF will give you a nice printout if you use their service. If you can't visit one of the locations they will be at, you can check out THIS site and learn more on the process of proper weighing and download a form to help you do the math. For those still questioning the need to know your actual tire loads, you might find these blog posts of interest. Loads & Inflation Part 1 Loads & Inflation Part 2 Seen at Mt Rushmore KOA

My suggestion on tire pressure for motorized RVs can be found HERE. I think there may be some confusion on the Michelin loads. The 255/80R22.5 XRV or XZE at 105 psi cold inflation is rated for 5,150 # each in single (front) position. The load rating for each tire is 4,685# each tire when used in dual fitment. Some tire charts give just the load capacity for each tire while Michelin gives the load capacity for each end of an axle.

NAPA NTH 907292 WW Grainger 6ZC63 Harbor freight 68215 SEARS SPM1189759601 Home Depot Model # 50238 Advance Auto & AutoZone do not carry this level of shop tool. Be sure to check the max air pressure rating before you buy for your tires.

Terry, as a PE maybe you can jump in. If we assume that a tire containing 95 - 98% N2 will have less pressure increase due to a temperature increase because the inflation gas is dryer, how do we get better fuel economy? Are the sellers of the N2 also claiming that lower tire pressure improves fuel economy? maybe we should all run out and lower our inflation to zero and everyone would get 200 mpg. Not.

Check out this post. The dryer or similar, is available at most auto parts stores and home centers. Go to their web site and search on DESICANT and you will see who hav the dryer and the psi rating.

"Scam" may be a bit strong as there is nothing wrong with filling your tires with less reactive gas like Nitrogen. The issue is that the claims used to justify the cost are only partially true and many are based on the assumption you never check the air pressure in your tires. If your tires were filled with Nitrogen you can top them off with air as needed. If you want to pay for going from 79% Nitrogen to 95% Nitrogen it is your money. I do not use the special gasses I have in my shop to inflate tires. I use regular air that has gone through a dryer.

I have read a few posts both here at FMCA as well as on other RV forum sites when the topic of what to do when a tire fails and you don't have a spare. Many times it has been suggested that the person plans on "limping" home or to the tire service center with just one tire in the dual position of their RV. While on the surface this might seem to be a reasonable approach, there are a few things that need to be considered. First, unless you have a TPMS that warned you that one of your duals was loosing air, in all probability you have no idea how long you drove with one dual underinflated. If you don't know when the tire started to loose you also have no idea at what speed you drove on one underinflated tire and also on one overloaded tire. If a tire looses more than 20% of its air it is considered to be "Run- Flat" by tire industry If you have driven on a "flat" tire it is considered to have been damaged and should not be considered for future safe usage. What is not obvious when you read the above is that is one tire of a dual goes flat the mate has now been overloaded. I covered some of the info in a post on the Special Considerations for Duals, but there is more that needs to be considered. If you have one tire punctured and loosing air the mate is "taking up" the load for both tires until it is 100% overloaded. Driving at highway speed will do serious internal structural damage. Most of which cannot be seen with out special equipment like X-Ray so it is simply considered scrap so now you need to replace two tires. Trying to "limp" means that you need to reduce your speed and according to the special tables in Tire & Rim Association for adjustments for speed, inflation and load your limp speed is not 30mph or 20 mph or even 10 mph but it is limited to 2 mph. That is TWO miles per hour Maximum. Any more and you are damaging your tire beyond repair. The solution would be to call for service. I would only drive on a single tire for a hundred yards at most to get to a location where I could safely pull off the roadway.

I posted some information on how to get reasonably dry air for your tires if the change in pressure is of concern to you. http://www.rvtiresafety.com/2012/05/how-to-get-dry-air-for-your-tires.html To help everyone here is what really happens to the "air" in your tires. The Nitrogen is less reactive than the Oxygen so the Oxygen tends to migrate through the rubber at a faster rate than the other gasses. In general all tires will loose from 1% to 3% pressure each month when all the variables are controlled in the laboratory. Temperature change has the biggest effect on pressure but Elivation and Barometric pressure also have an effect. We have run experiments where we measure the %N2 in a tire and over a period of a year as the O2 "leaks" out and more air is added to maintain the tire inflation level the net effect is to increase the % N2 in the tire air chamber by a couple %. This is measurable but not really meaningful in the big picture. By the time you increased the N2 % to say 82 or 84% the tires would probably be be worn out or over age.

Nancy Bretts coments are correct. To you and others concerned about needing a compressor on the road I am not really sure it it is necessary or the best way to allocate your money. If you are going to spend a few hundred you would be much better off investing in a TPMS that will give you low pressure warning even while driving. While setting the correct pressure is a "Hot Topic", if you have done the basics of getting the actual corner tire loads and confirmed the minimum cold inflation then add 10% cushion. All tires will loose are but only at about 1 or 2% per month so unless you have a leak or puncture you should be good for at least a couple of months or more between needing any air at all. Pressure will change with temperature http://www.rvtiresafety.com/2012/04/how-do-i-know-what-my-hot-pressure-and.html Only a little bit with elevation so you should not need to be adding air till you have lost at least 5% of your cushion. If you discover you have lost 10 to 20% of your air over a day or so since you last checked your pressure, you have a more serious problem and the problem needs to be fixed. If you are loosing air that fast a compressor will only give you enough air for a short drive and driving on a puncture or damaged tire could lead to more damage or even a blow-out. Bottom Line Once you properly inflate your tires you should be able to get them aired up for free every few months and never need a compressor.

If you look at the statements from the tire mfg they basically do not want "stuff" that can harm the tire to move to the tire and hurt it. Oil from asphalt or water from dirt/sand. It isn't the grass but the moisture that can migrate into the tire over time from the dirt or sand. I would think that pavers would be reasonable. Personally I have some 2x10 that are large enough to support the complete footprint that I place over the gravel where I park for the winter. Inflating the tires to their max is a good idea. If you can remove some of the load that would decrease the rubber "set" that can occur too. Don't forget the white tire covers to protect against excess heat and UV and no electric motors or devices like ozone generators near the tires or in the same garage if indoors.

Not sure why HF changed the link but here is the P/N if you need less than 90 psi: item#68215 1/4" pipe threads are standard on most air chucks. Also I keep mine in a ziplock bag so the desiccant is good all Summer. There are similar products available at many auto parts stores. just ask for air dryer for air tools. Note the HF "filter" P/N 68224 is not a desiccant as it filters out moisture that has condensed in your compressor or air lines. You have given me a good topic for a blog post. Give me a week or so to do the research.

I think I covered most if not all the questions in my blog on Nitrogen. Bretts comments on dry are are very appropriate.

Was the dealer a company store or independent dealer? If company store you might be able to get some assistance from BFG on getting the tires changed to the H load range you need to carry your load. The Utah dealer should know better. RE Mixing brands: In a pinch I might do it on the front but would really prefer to have all tires on an axle the same brand, size, and load range. For duals you have a couple of things to consider. 1. Their history... See this post. 2. Their circumference. While inflated but not loaded you need to ensure that both tires in a dual position are within 3/4" measured circumference.

Hi Phil, First off be happy your RV manufacturer provided you with tires that can easily carry your loaded weights. Too many owners discover they have been sold a unit with tires that are almost in overload as soon as they leave the dealership and fill the tank with gas/diesel. Now to your specific question. I agree with the info provided by both Andy and Brett. While my thought process is slightly different we end at essentially the same end point. Start out no lower than the lowest inflation on the Michelin chart. The only exception to this would be if you get something IN WRITING from Michelin corporate (NOT THE LOCAL DEALER). Since you don’t have actual individual tire loads of the fully loaded RV I suggest the following: Assume a side to side variation of at least 5% so you calculate a 55/45 split. Using the 55% of total load I check the company tables to find the minimum inflation needed to carry that load. NOTE you are going up in the inflation in the table to the PSI that exceeds your calculated load. For those pulling a multi axle trailer you also need to assume a 55/45 axle to axle load split before you do the 55/45 side to side split. I then add at least 5% to the table inflation and again round up to the next 5 psi to allow for daily temperature variations and to have an easy to remember inflation number. This extra 5% means you are not chasing your tail and trying to calculate and adjust the pressure every day. Remember all tires will loose 1% to 2% air each month in addition to the variation due to temperature, elevation and minor variations due to barometric pressure. So unless you enjoy spending a half hour every day calculating and adjusting your pressure just add the extra 5% so you only have to add air every couple of months or so. FYI If you are going to FMCA Int’l Family Reunion in Indianapolis check the schedule as we are reviewing the schedule and I think I will be presenting my Tire Basics for the RV Owner on Tuesday. If you make it be sure to say Hi.

Brad Where did you find the data indicating "extra side-wall". I see thicker rubber to protect against you running against curbs but this will also increase heat generation, I find in the 255/80R22.5 XZE* LR-H 5510# @ 120 psi and 18/32 tread depth XRV LR-G 5205# @ 110 psi 16/32 tread XZE LR-G 5205# @ 110 psi 20/32 Not quite Apples to Apples with three different read depths and two different Load Range. I think if you read the sidewall you will see the actual constructions to be one ply of steel in all three tires. Note the extra tread depth will probably lower fuel mileage. When I read the Features and benefits info I would think you want longer sidewall life (ozone resistance) rather than heavier tread depth, unless of course you wear out your tires before they age out.

Harry Brett is correct. There are a lot of BUBBAS out there. If someone ever sold a tire or got paid to change a tire I guess they are entitled to call themselves "professional" but I would certainly not consider them "competent" to perform a meaningful tire inspection. Having taught hundreds of tire "professionals" and engineers in North, Central and South America I can attest that few have spent the time needed to learn much of the art involved with tire inspection. Finding a person competent to do "end of life" inspection is just as hard as finding a competent heart or brain surgeon. Just knowing how to handle a scalpel does not make you competent in all forms of surgery. But none of this helps you. So to your question. First off sidewall cracks are seldom, in themselves, the root cause of a tire failure. Just as high blood pressure is not the “cause” of a heart attack. BUT just a high blood pressure can be a symptom that suggests hidden issues that might lead to a heart attack, the sidewall cracks are an external sign of the higher probability of internal structural issues that could be of concern. There are two areas of concern in the tire structure and they are close to each other. At the edge of the belts in radial tires, where the most heat is generated the heat does cumulative, irreparable weakening of the rubber in that area. This loss of strength can ultimately lead to microscopic cracks which will grow with time and use. If the cracks get large enough the surrounding rubber can tear and then you may get a detachment of the tread from the belts or between the belt edges. Here is a picture from the NHTSA publication. This tire has not come apart yet but will do so if the owner had continued to drive on this tire. The Pneumatic tire pg 627 This is a very technical 700+ pg document. Will give most non-tire engineers a headach, but I do need to provide the source for this picture. Now there are inspection procedures using X-Ray and Holographic inspection machines but the cost of doing such an inspection would probably exceed your cost of a new tire so many time it is simply less expensive form of “insurance” to replace the old tire when the external warning signs such as cracks exceeding the size established by the manufacturer or the tire has reached the manufacturer’s recommended maximum useful life. Sometimes it is possible for a very experienced tire inspector to see signs of impending failure on the exterior or interior surface of the tire but while the presents of such indicators may suggest a high probability of impending failure, the lack of these signs is no guarantee there are no internal structural issues. Following the “better safe than sorry” philosophy means that once the tire has reached the recommended age limit and or is showing excessive levels of external cracking it is time to replace the tires. I would consider the replacement just like insurance. You don’t plan on having an accident but driving without insurance is a risk few are willing to take. If you are not sure who to trust, then I suggest you find a tire store owned and run by the tire manufacturer and not just “Bubbas bait and tire discount store” for it is more likely that someone working for the manufacturer will have received at least a little training on in the art of tire inspection. You can always get a couple of opinions too if that will make you feel better but at 8 years the clock is ticking pretty loud. If your tires still look good the dealer might even find a buyer that tears up his tires in dump truck or trash hauler service.

Spec is 1/4" but in real life few have the tools to accurately measure the Diameter. Once the tires are off the ground you can more easily measure the circumference and check that they are within 1/4". Note dimensions published are new tire and all tires grow a bit but all at different rates so you really can't compare published dimensions. Especially across two companies. More info of the special considerations for duals HERE.

I agree with Brett, but would like to expand on the topic a bit. I think it best to think of a tire "Max speed" a bit like the engine red line. Can you exceed the red line on your engine? Yes, occasionall,y but is it good for the long term durability of your engine to run at the red line? I think you will agree that that is not a good policy. A tire has a finite life and heat and cycles consume that life. Heat comes from under inflation, overloading and fast speed along with spending all your time in the South. Heat generation occurs inside the tire structure at the molecular level. It is not linear so 1 mile at 75 “uses up” more of that limited life than 2 miles at 40. It’s even possible that a mile at 80 is worse than two at 60. The max speed rating is also based on the assumption that the tire has NEVER been operated while “flat”. Note that a loss of 20% of the minimum inflation needed to carry the load is considered “flat”. Also if the tire has ever been repaired the manufacturer may no longer support the speed rating marked on the tire. You need to consult the manufacturers publications to confirm their policy. This would apply to tires with a Speed Symbol letter as found on most Class-B & Class-C motorhomes and a few Class-A units. An example might be LT235/85R16 LR-E 116/120Q The 120/116R is the Service Description with the 116 and 120 being the Load Index and the “R” being the Speed Symbol for 99 mph. Class A might have 255/70R22.5 LR-G 138/134L the “L” is the Speed Symbol for 75 mph. I know of no highway tire that can run its entire life of 40 to 90,000 miles at its max speed. The tests to establish the Speed rating only require an hour or so to complete and most of the test time is well below the max. Finally. If you tow a trailer or dolly that has ST type tires you need to remember they are rated at 65 MPH max and a few trailers come with commercial tires that are only rated to 62 MPH so your max speed is based on the lowest rating of any single tire.

I understand the alternate interpretation of "Gross weight" as possibly applying to the load on each tire but that doesn't make sense either, as the full statement from RVDA is "Independent braking system is required in each weight bearing wheel where gross weight exceeds 1,300 kg (2,867 Ibs). Breakaway brakes are required on all trailers 1,360 kg (3,000 Ibs) and over." If we are talking individual tires then heavy trucks would need as many as four "independent braking systems" which I am confident is not the case. I have never heard the term "gross weight" being applied to individual wheel positions. I tried asking Société de l'assurance automobile du Québec for a clarification but they just directed me to a page with most or all traffic laws in French. What I believe we have is a failure to get an clear and accurate translation. Too bad I can't find this within FMCA. I have learned that a number of provinces would seem to require electric brakes that "can be applied by the driver" which would seen to preclude surge brakes. http://drivinglaws.a...trailer-brakes/

Found this Quebec requirements say "Independent braking system is required in each weight bearing wheel where gross weight exceeds 1,300 kg (2,867 Ibs)." This would mean I need three "Independent" brake systems. One for the RV, One for the Dolly plus one for the reat tires on the car. http://www.rvda.ca/ProvBrakeReqts.asp Looks like Tow Dollies are not an option in Quebec.

Hadn't heard about the "all axle have brakes" requirement. Can anyone shed some light? This sounds like a wonderful one page info sheet for FMCA to publish. While we are not planning on All states we do plan on Canada in next few years. If I don't do Dolly I have to buy a new car or not tow.