tireman9

HERE are the numbers on the temperature reduction you can see with white covers. If you have an IR gun you can do your own test. I tried to simulate dark covers HERE. Some complain that since I didn't go out and buy a set of dark covers, my simulation was of no value. I would be interested to see results from someone who has black covers. RE the life of black plastic vs white, I would guess that it really depends on the polymer used as to the UV resistance. How many of us have ever heard anyone advocate black rubber roof on our RVs?

Don't forget that just because you checked the air in the morning or in the rest stop doesn't mean you won't drive over a nail as you pull out of the driveway.

A little more about DOT code and manufacturing plant location at this site. Note that the first two characters are the plant code and does not change. The next two are usually a code for tire size but this code is not universal and sometimes tires of the same size may have different "size code" when made by two different manufacturers. Finally if you only have three numbers at the end of the DOT serial that means the tire is more than 11 years old and should not be on any RV driven on the road today. I have a blog post specifically on tires made in China. Also a post on why "bad tires" are on the road.

As a tire design and quality engineer I find the test run by Powertank sound. Having this data available will make it easier to explain that while there are some advantages (dry air) to N2 but other than that I am not aware of those claims being based on controlled tests. The fact that the results show no advantage for CO2 in the results should put to rest concerns about the company running the test.

Ratings for a Michelin 275/80R22.5 are interesting The LR-G at 110 psi is rated at 6175# Single and 5675# Dual The LR-H at 120 psi is rated at 7160# Single and 6610# Dual The Michelin specs show both LR-G and LR-H at 40.1 OD and 10.9" wide when measured on a 8.25 wide rim with a 12.2 dual minimum spacing. The dual spacing is controlled by the wheels so you will need to contact the wheel mfg. You can learn more of wheels at http://www.rvtiresafety.com/2011/12/wheel-is-just-wheel-isnt-it.html What is interesting is that industry standards show a 295/75R22.5 with the same load capacity in LR-G but slightly lower load capacity at LR-H 6610# and 6005# The 295 normally has an OD of 39.92 and width of about 11.4 if olso on a 8.25 rim so the warnings on dual spacing are something you really need to consider to avoid problems. RE matching duals. You should ALWAYS measure the OC of any tires you are considering mating as a pair. The OC must be within 3/4" of each other or you are asking for trouble. Do not count on the larger tire wearing down faster to get a matched pair. Deeper tread runs hotter. The larger tire is a dual pair will carry more load so this adds more heat. heat is the number one ennemy of tires. One thing to include in your investigation is the real load you carry on each end of an axle. You should never consider going down in load capacity as even if you always run light load the next owner may laod his bowling ball collection and just assume the tire size you selected is OK. The next owner could have tire failures because of your decisions.

I suggest that people in the market for a TPMS do more than price compare. There are a number of questions to ask. Length of warranty Are batteries replacable? Cost of batteries vs cost of new senders Life of batteries Will you need a signal repeater ( probably yes if over 35' and definately if you are also monitoring the toad) How easy is it ( $$$?) to install the signal repeater? Does the TPM only have one low pressure warning setting? i.e. Do you get warned as soon as the tire looses a few pounds from the hot running pressure or only after you have lost 15% of the cold setting pressure?

While I don't quite agree with everything previously posted there are a couple reasons for the loss in mpg and the "squirm" feel. I also do not feel the tires are "defective" as you are experiencing results that are seen in all tires. Even if you were to take two sets of new tires that had the same heat history but one had most of the tread cut off, the tires with the shallow tread will deliver better fuel economy because the movement of the thick tread consumes more energy (rolling resistance) than the tire with less tread rubber. Second it is well documented that the shallower the tread the crisper the handling. What you are really feeling is the result of tread element rubber bending and moving as you drive down the road. Tire wear rate is not linear and the wear rate when new is faster than after a tire has worn some of the tread off. For street use the only "seasoning" I would think is of concern, probably occurs in the first hundred miles or so. This is when the tread release chemicals used in tire manufacturing wears off. This is a very thin coating so I don't think you need to wait 7,000 miles. I believe the Michelin rep was trying to give you an estimate of when the feeling will get close enough to the old, worn tires that the difference will be almost unnoticeable.

According to the Michelin Load & Infl tables your 235/80R22.5 LRG XRV®, XZE PSI 70 75 80 85 90 95 100 105 110 Maximum load & pressure on sidewall LBS Single 6940 7290 7720 7950 8280 8600 8910 9220 9350 S 4675 LBS at 110 PSI Dual 12640 13260 14100 14460 15060 15880 16220 16780 17640 D 4410 LBS at 110 PSI Note the above are axle ratings not tire ratings. Now you didn't advise your actual corner loads or the placard inflation for your Damon so it makes it difficult to provide an exact suggestion. Goodyear has a 255/70R22.5 H showing 80 85 90 95 100 105 110 115 120 S 4190 4370 4550 4675 4895 5065 5205 5400 5510(H) D 3970 4110 4275 4410 4455 4610 4675 4915 5070(H) Bridgestone has an R195F 255/70R22.5 H Firestone has a FS560 Plus and an FT455 Bother the Bridgestone & Firestone have the same Load 7 inflation ratings as the Gooyear. You do need to confirm the "dual spacing" and this is controlled by your wheels so you need to get the actual part number and confirm with the wheel manufacturer. You do not want to have less than the minimum spacing specified by the tire manufacturer. Both wheel width and offset of the wheel need to be confirmed to confirm no spacing issues.

rdtripn, Just to add a minor clarification on getting the RV weight. Some people try and cut it very close and think they need to weigh and adjust inflation every trip. It really isn't that imporatant as long as you are not overloading the tires or suspension. It is suggested that when you are ready to get the corner weights you have a full fuel & LP, the clothes and food you would pack for a long trip and have the water full. Also, all people and pets in their normal "travel" location. Now if you dump your holding tanks before leaving the campground then you don't have to worry about getting the weight with anything in the holding tanks. Here is a link to a page that has general RV info and a very good worksheet on how to calculate corner weights. It covers just about every combination of Motorhome or truck & trailer. Knowing the minimum inflation at your heaviest loading and setting all tires on the same axle to the same inflation based on the heavier side and adding the 5 psi Brett mentioned will mean that when you empty your fuel tank or eat all that food you will not be overloading the tires. Underloading in this case is OK.so you don't need to adjust the inflation down. Remember check your air with a good gauge each morning before you travel and consider getting a Tire Pressure Monitor System that can warn you if you get a puncture and slow leak.

Michelin North America, Inc., announced Thursday July 26 it is voluntarily recalling about 841,000 BFGoodrich commercial tires LT 235/85 R16 120 Q LRE and LT 245/75 R16 120 Q LRE, and Uniroyal Laredo tires LT 235/85 R16 120 Q LRE and LT 245/75 R16 120 Q LRE. The tires were produced between April 2010 and the end of July 2012. Consumers can call 800-637-5527 or visit http://www.bfgoodric...arysafetyrecall or http://www.uniroyalt...arysafetyrecall. More info at http://www.cnn.com/2...call/index.html While looking for details on the Michelin recall, I also came across info on a number of new in July recalls on a variety of RVs including PREVOST, ENTEGRA, TIFFIN, SAFARI COACH, BERKSHIRE, and CHARLESTON. More info can be found at http://www-odi.nhtsa...lls.cfm?start=1 There are also a number of other vehicles included in the current July recall list with 44 separate recall notices involved. You might want to check the list to see if you own a covered vehicle.

N2TYRZ Please repost or correct the 2nd link it does not work. I note the claim "nitrogen inflated tires improve tire life by about 50% and vehicle fuel economy by 23%." I find this hard to believe given the current level of effort and importance placed on rolling resistance by OE vehicle manufacturers. Many times a 1% improvement in Rolling Resistance is enough to gain a multi million dollar tire contract. In my article published in Tyres International I cover the status of Rolling Resistance and you can see that there is no room to see a 23% improvement simply by changing 28% of the inflation gas from O2 and CO2 to N2. If these numbers presented by a college student in 2007 were accurate we would see 100% of all new vehicles come with Nitrogen inflation, but we don't. Another problem is the failure to use accepted test machines to measure Rolling Resistance but to rely on highly variable over the highway fuel economy calculations. Reviewing the air leak tests I find it interesting that there was actually a pressure increase in fig 5.8 on pg 59 between the second and subsequent measurements. This to indicates some fault in the test procedure. For the truck tire test three different vehicles with three different drivers and three different pressure gauges were used. It is expected that air will leak at each pressure measurement and anyone that has ever measured tire pressure knows that sometimes you get a good reading with minimal leakage and other times the leakage is greater. This is just another variable not taken into consideration. The biggest problem I have is the use of pressure change to predict Rolling Resistance change and therefore it is assumed fuel economy would be similarly improved. The other assumption is that a vehicle operator would not adjust the air pressure in the tires back to the proper inflation but would continue to drive on a tire with lower inflation than specified. Tire life is really a tread wear estimate. The results were based on a one month test of an estimated 2500 miles and an approximate tread wear of 0.005". Having done thousands of tire tread measurements I can assure you that contact measurement gauges are simply not accurate enough to provide reliable measurements at that level. Bottom line. In my opinion inflation with N2 is not a bad thing. It is even theoretically a good thing but to make outlandish claims of 23% fuel economy improvement and 50% improvements in tire "life" are not supported by the data presented or by decades of tire and vehicle industry testing.

I still have to wonder about the claim of "Improved" fuel economy with the use of N2. It is well established science that any given tire will have improved (lower) Rolling Resistance (RoRo) with an increase in inflation pressure. RoRo is the force that impacts vehicle fuel economy with increased force resulting in lower mpg. If inflating a tire with N2 results in a more stable (less increase due to temperature) inflation pressure, where is the data that shows that somehow the improvement in RoRo with an increase in inflation pressure no longer exists when the inflation gas changes from 78% N2 to 95% N2. Not saying that constant inflation pressure with N2 doesn't result in improved RoRo, just haven't seen any data. Maybe someone can educate me.

See my post on where to get air.

I did a post on getting free air. Some with large RVs have on board compressors for air bags or brakes or jacks and simply have an extra fitting added to their system. Others who have Class-C that run Light Truck tires that need 80 psi or less can use a $25 to $50 Harbor Freight compressor or similar. But I would ask why do you need air? If you are running the +10% that I suggest above your minimum as calculated from your actual tire load numbers and you check air each day before travel and have TPMS you should see that you are approaching your minimum goal days in advance which gives you time to top off the tires at a truck stop or tire store. Normal day to day change due to temperature should be normally in the +/- 3 to 5 psi range. If you note the cold inflation in the morning is a few psi low then write down the number of psi you need to get back to your +10% level, then when you stop you write down the hot inflation and add the number of psi needed from your morning check plus 1. I think you will find you are +/- 2 of your goal the next morning when you confirm your cold level. If however you discover you have lost 20% from your goal then you really need to call for service as driving on a tire when 20% low is considered to be driving on a flat tire and you can be doing damage plus you need to find out why you lost 20& of your air in one day.

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.