pjhannon Report post Posted June 11, 2016 I have a question about my new to me Class A. The outer edges of all 4 rear tires are wearing enough to lose their tread marks. The coach says to run 80lbs and these are inflated to 95lbs. What do you think? The tires say maximum pressure 125lbs. They are a low time looking matched set of Chinese tires. My gut feeling is to raise the pressure to stop the outer edge wear. However we are way over the coach placard pressure of 80 lbs. This is a new coach to us and we are figuring things out. Share this post Link to post Share on other sites
wildebill308 Report post Posted June 11, 2016 Welcome to the forum. The first thing I would do is weigh the coach. Once you know how much you weigh (4 corner weights are better) you can properly adjust your tire pressure. Personally it sounds like you need more pressure. I would also check the load range of the tires. Bill Share this post Link to post Share on other sites
blakeloke Report post Posted June 11, 2016 Welcome to the forum. I agree with Bill. You may not be able to find anyone local that can give you corner weights on your tires but a truck stop like TA/Petro with a CAT scale can give you axle weight. Take your axle weight and divide by the number of tires on that axle. Then look up load rating vs air pressure for the make and model of your tires (hope it is available). I would be suspect if your loads require higher PSI but previous owner only ran 80. Especially if the outside of the tires are seeing unusual tread wear. I'm not sure how old your tires are but you might check the manufacture date on the sidewall. If over 5 years old, have a qualified tire service center inspect for serviceability. Blake Share this post Link to post Share on other sites
tireman9 Report post Posted June 24, 2016 RE your specific question of shoulder wear.vSince we are talking rear duals it is not an alignment issue so all that is left is load & inflation. Others have suggested you confirm the correct inflation for your actual load. The 80 psi is the suggestion from the coach Mfg but that is based partially on an estimate on how much "stuff" you are carrying. I have never met a person with "calibrated" eye sight that can tell you the actual load on an RV axle or tires so getting on a scale is needed. Having at least the air pressure needed to support the actual load on your tires is a foundation to having the best over all performance from your tires. HERE is a worksheet posted by a friend of mine. He focuses on 5th wheel trailers but the form covers all types of RVs. He even posts a video of what is involved and a list of weigh providers. Now the posts above point out the problem of locating scales where you can get the one side only weights as seen in the form. But the good news is that you have some options. Some states like WA & OR leave their scales on 24/7 so you can take your time collecting the readings you need to do your own calculations. Some have reported sucess in contacting local State Police for location where they are checking truck weights so give that option some consideration At FMCA Int'l family Reunions RVSEF offers a great service and they will not only give you the weights but will do the calculation for you. Check out their web site for their schedule. You might also review some of the posts on my blog on weight and inflation to learn what I believe is good practice. Share this post Link to post Share on other sites
wigginsjsr Report post Posted June 24, 2016 Many moving and storage companies have scales that are level and give you the capability to weigh one side at a time. Try your local yellow pages. Share this post Link to post Share on other sites
pjhannon Report post Posted August 20, 2016 Thanks all of you for your help. I need to get it weighed so it is a logical starting point. Share this post Link to post Share on other sites
hermanmullins Report post Posted August 20, 2016 Weighting 4 corners and getting the recommended pressure is the way to go. For me the rule of thumb for tire wear has been, cupping. .shocks or balancing, inner or outer wearing..alignment, both edges wearing equal..too little air pressure and center wear..too much air pressure . Maybe just old school. Herman Share this post Link to post Share on other sites
manholt Report post Posted August 20, 2016 Herman. Nothing wrong with "Old School"! I think, these days we can get too technical... Share this post Link to post Share on other sites
wildebill308 Report post Posted August 21, 2016 Till you have the weights, and know what you should /could run I would run the max pressure recommended on the sidewall. Bill Share this post Link to post Share on other sites
wolfe10 Report post Posted August 21, 2016 Another option until you have your weights is to run PSI recommended on your GVWR plaque. The PSI on that plate is for each axle loaded to its Gross Axle Weight Rating. Yes, if you are overloaded, this will be too little PSI. We don't know what coach/chassis you have, so do not have a feeling for whether you are likely under or overloaded. Share this post Link to post Share on other sites
manholt Report post Posted August 21, 2016 Hope we have not lost OP! Carl Share this post Link to post Share on other sites
bm02tj Report post Posted August 22, 2016 You need to check your gauge as well. Share this post Link to post Share on other sites
