house Posted August 11, 2015 Report Share Posted August 11, 2015 How much air are you running on your drive axles? I just got back from my first trip with my new to me HDT and it seemed Like the rear end was a bit "loose" the previous owner towed a relatively light TT and had taken off the inside dual tires. After adding a new tire and wheel to it the Truck shop told me that i should only run 100psi because I am just pulling a horse trailer. I have not weighted it yet but my FL50 was about 20K loaded so I would guess the HDT would be all of that and maybe a bit more. The other though I had is that the outside tire the PO had on it was a china brand tire that is brand new, but I have never had great luck with them and am debating replacing them with a kumo tire. I guess I will try 120 psi first and see if that makes a difference. Also I am going to take the truck in to an alignment shop near me to have the front end gone through, it seems like there is a bit more slop in the wheel than i would like. Link to comment Share on other sites More sharing options...
rickeieio Posted August 11, 2015 Report Share Posted August 11, 2015 Consult the tire makers inflation chart. You'll likely be below the lowest weight they publish, so just go with their lowest. Of course this means you need to know axle loads. KW T-680, POPEMOBILE Newmar X-Aire, VATICAN Lots of old motorcycles, Moto Guzzi Griso and Spyder F3 currently in the front row Young enough to play in the dirt as a retired farmer. contact me at rickeieio@yahoo.com Link to comment Share on other sites More sharing options...
TreyandSusan Posted August 11, 2015 Report Share Posted August 11, 2015 Just what rickeieio said, and to add - the only weigh to know the axle loads is to put the tires on a scale. It is highly likely you will be near or off the bottom of the chart. We run 70-75 psi but that is based on our measured loads. Everyone's loads are different. Susan & Trey Selman | email | HDT: '01 770 VED12 | 5er: '02 40' Travel Supreme RLTSOA | '16 Piaggio MP3 500 | '15 Smart Cabrio | Personal Blog | HHRV Resource Guide | HHRV Campgrounds | Recreation Vehicle Safety & Education Foundation | Link to comment Share on other sites More sharing options...
Phil D Posted August 11, 2015 Report Share Posted August 11, 2015 I agree with Rick and Trey. According to most manufacturers' charts, which typically don't go any lower than 70 PSI, the vast majority of us will be somewhere between 70 and 80 PSI, according to our tire loads. You'd have to have far more pin weight than any fifth wheel could impose to come anywhere close to needing 100 PSI in duals, unless you've downsized to an MDT-appropriate tire on your drive axle. Phil 2002 Teton Royal Aspen 2003 Kenworth T2000 - Cat C12 380/430 1450/1650, FreedomLine, 3.36 - TOTO . . . he's not in Kansas anymore. ET Air Hitch Link to comment Share on other sites More sharing options...
Star Dreamer Posted August 12, 2015 Report Share Posted August 12, 2015 Nick are you saying the previous owner removed the inside duals so that you are only running the outside tire at the rear? Are you still tandem axle? (we hope so). You also mentioned a new outside tire, is this on all rear axles or just one tire? Also is this a drive type tire with large lugs? If so, you may experiencing an issue like 1Rod had when he got new tires, the real deep lug was giving him an unusual feel and took some miles to wear in. Also you did not say what China brand tire you had, just curious why you think Kumho's which is a Korean manufacturer (not sure if that is where they are made at) is better than Chinese made? Most comments we see are to go to USA made. We are not knocking either, just curious. Dave 2005 Freightliner Century S/T, Singled, Air ride ET Jr. hitch 2019 46'+ Dune Sport Man Cave custom 5th wheel toy hauler Owner of the 1978 Custom Van "Star Dreamer" which might be seen at a local car show near you! Check out http://www.hhrvresource.com/ for much more info on HDT's. Link to comment Share on other sites More sharing options...
house Posted August 12, 2015 Author Report Share Posted August 12, 2015 Star dreamer, the truck just had the outside dual when i bought it, I put on a yokohama ty517(sorry i thought it was a kumo tire) on the inside. so it has duals now and is singled, in my experience the name brand tires do better than the yellowseas brand tire that was on there.... as for US made i have had my fair share of issues with US(g614) tires but the no name china brands are worse. I checked my load rating and like i said my rear axle was over 20k on my fl50 so unless my c112 is lighter i think i am at or near the tire pressure rating for the tire. I think i am going to try to bring the tires up to 120 psi and see if that makes a difference. I am curious to know what some off your rear axle weights are if you only running 70 or lower psi. Link to comment Share on other sites More sharing options...
JC and Angie Posted August 12, 2015 Report Share Posted August 12, 2015 If he has 20k on the single rear axle then he is correct that 100psi is the right psi for the tires. Ask trey how I know this ! ! 2009 Volvo 780. D-16 500hp 1850 torque with a Herrin hauler bed. 2015 Continental Coach 2008 650cc Suzuki Bergman 2013 Mustang GT 500 convertible 2014 Smartcar convertible WWW.Hollyfab.com. (Metal Fabrication Company) Jamesc@hollyfab.com (preferred contact method) Link to comment Share on other sites More sharing options...
Phil D Posted August 12, 2015 Report Share Posted August 12, 2015 Yes, 20k on a single rear is far more rear axle weight than most of us have. 100 PSI or more could easily be in the ballpark for that kind of weight. Phil 2002 Teton Royal Aspen 2003 Kenworth T2000 - Cat C12 380/430 1450/1650, FreedomLine, 3.36 - TOTO . . . he's not in Kansas anymore. ET Air Hitch Link to comment Share on other sites More sharing options...
RandyA Posted August 12, 2015 Report Share Posted August 12, 2015 Kumo's are mostly made in China even though they are a Korean company. Just because they are made in China does not mean they are inferior or the proverbial "China Bombs" similar to what ends up of many towable RV's. IMHO, you can get a decent tire from China IF the tire construction is controlled by a reputable known tire manufacturer and not some company trying to save a buck by not having good QC or taking shortcuts on construction. I have Crossfire equalizers set to 80 psi installed on my drives and they are wearing well. This is a link to an interesting web site that you can use to identify where a specific tire was made. Randy, Nancy and Oscar "The Great White" - 2004 Volvo VNL670, D12, 10-speed, converted to single axle pulling a Keystone Cambridge 5th wheel, 40', 4 slides and about 19,000# with empty tanks. ARS - WB4BZX, Electrical Engineer, Master Electrician, D.Ed., Professor Emeritus - Happily Retired! Link to comment Share on other sites More sharing options...
CrazyCooter Posted August 12, 2015 Report Share Posted August 12, 2015 10-11k on the rear axle @ 55 psi and 10k on front @ 95 psi in low pro 24.5s 1999 Peterbilt 385 C12 430/1650 13spd 2006 Dodge 3500 DRW 4x4 2010 Hitchhiker Champagne 36 LKRSB Link to comment Share on other sites More sharing options...
NoDirectionHome Posted August 12, 2015 Report Share Posted August 12, 2015 I checked my load rating and like i said my rear axle was over 20k If he has 20k on the single rear axle then he is correct that 100psi is the right psi for the tires. Two totally different things... Yes your axle may be "rated" for over 20K lbs, but you only need tire pressure to support the "actual" load the tire is carrying. "There are No Experts, Do the Math!" 2014 Freightliner Cascadia DD16 600hp 1850ft-lb 18spd 3.31 260"wb SpaceCraft S-470 SKP #131740 Link to comment Share on other sites More sharing options...
house Posted August 12, 2015 Author Report Share Posted August 12, 2015 When I drove my fl50 over the scale on 70 in Colorado last year my rear axle weight was 20,400. on a side note why on earth does everyone have to stop there? I have never seen that sign that says all towed vehicles must stop. I think it is pretty new. Link to comment Share on other sites More sharing options...
Tireman9 Posted September 2, 2015 Report Share Posted September 2, 2015 Star dreamer, the truck just had the outside dual when i bought it, I put on a yokohama ty517(sorry i thought it was a kumo tire) on the inside. so it has duals now and is singled, in my experience the name brand tires do better than the yellowseas brand tire that was on there.... as for US made i have had my fair share of issues with US(g614) tires but the no name china brands are worse. I checked my load rating and like i said my rear axle was over 20k on my fl50 so unless my c112 is lighter i think i am at or near the tire pressure rating for the tire. I think i am going to try to bring the tires up to 120 psi and see if that makes a difference. I am curious to know what some off your rear axle weights are if you only running 70 or lower psi. When you added the 2nd tire to the dual position did you do a proper "matching" of the tires in the dual application? i.e. same size, brand, design AND have a measured OC within 3/4" of each other? If not then you may be asking for problems as the load and traction will not be the same for both tires in the dual position. Check out my Blog www.RVTireSafety.NET I serve on Tech Advisory board of FMCA as their Tire Expert. Give three different seminars on tires at RV events and I also give three seminars on Genealogy too. Link to comment Share on other sites More sharing options...
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