darren. Posted April 23, 2014 Share Posted April 23, 2014 I have a 92 Horizon ST that I love (obviously). Just curious what people suggest as proper tire pressure. On the wheel it says 65 PSI, but when I put it at that level, it seems super low. Is this normal? Quote Link to comment Share on other sites More sharing options...
linda s Posted April 23, 2014 Share Posted April 23, 2014 65 is max pressure for most of our tires. Can't go higher and if they still look low I would check your gauge. What are you inflating them with. Gas station? home air compressor? Linda S Quote Link to comment Share on other sites More sharing options...
darren. Posted April 23, 2014 Author Share Posted April 23, 2014 I filled them at the gas station, and checked them a bunch of times. I'll drop them to 65 and see how it feels for a few days Thanks! Quote Link to comment Share on other sites More sharing options...
linda s Posted April 23, 2014 Share Posted April 23, 2014 Tell me what tires were talking about. Brand and exact size. Do front or rear look low or both Linda S Quote Link to comment Share on other sites More sharing options...
DanAatTheCape Posted April 26, 2014 Share Posted April 26, 2014 Assuming you have D rated tires , your max PSI should be 65. If that is what is printed on your tires I would not exceed it. Most of these campers are at if not exceeding their max gross rate. My tires look "low" too. Quote Link to comment Share on other sites More sharing options...
darrel Posted April 26, 2014 Share Posted April 26, 2014 You mention 65psi as max. That would mean to me that you have "D" rated 8 ply tires. This is the recommended tire size. I always check tire pressure with two or more types of pressure gauges. If you rely on one or two, three gauges of the same brand you could still get false readings. I run 60 psi and have never had a problem, not even a flat. 70,000 plus miles. Quote Link to comment Share on other sites More sharing options...
darrel Posted April 26, 2014 Share Posted April 26, 2014 Forgot to mention I have a 94 Winnebago Warrior. The manual and a sticker on the door says for tire size "Suitable Tire & Rim Choice 185R14-LT6 50psi Front & Rear." You will get a smoother ride and poorer gas mileage not to mention less load carrying capacity. The LT6 means Lite Truck C rated tire. Quote Link to comment Share on other sites More sharing options...
DanAatTheCape Posted April 29, 2014 Share Posted April 29, 2014 my 93 WW has the same placard - 6 ply tires (now called "C" rated) are not as readily available as 8 ply (D rated). I prefer the D's as these campers run around quite heavy anyway. D's usually max at 65psi Quote Link to comment Share on other sites More sharing options...
Derek up North Posted April 29, 2014 Share Posted April 29, 2014 Load Range D tire ALWAYS are rated at 65psi maximum. You do NOT have to run 65psi. Quote Link to comment Share on other sites More sharing options...
Vanman Posted April 29, 2014 Share Posted April 29, 2014 My RA08's say 185R14C on the side but according to Hankook, are 8 ply rated, and the C means commercial. They also have nowhere near 8 plies any more.john Quote Link to comment Share on other sites More sharing options...
Derek up North Posted April 29, 2014 Share Posted April 29, 2014 The 'X-ply' rating system goes way back to the 'dark-ages' of the cross ply days. Possibly, at some time, '6-ply' actually meant there were 6 plies. That's why I usually chose to use the 'Load Range X' description. Quote Link to comment Share on other sites More sharing options...
Gulfstream Greg Posted May 5, 2014 Share Posted May 5, 2014 Should be a max psi on the side of the tire! Quote Link to comment Share on other sites More sharing options...
zero Posted May 9, 2014 Share Posted May 9, 2014 I have a 92 Horizon ST that I love (obviously). Just curious what people suggest as proper tire pressure. On the wheel it says 65 PSI, but when I put it at that level, it seems super low. Is this normal? Optimum tire pressure is determined by how much weight is on the tire. The ground pushes against the tires and the air pushes back. If you over-inflate by 20 PSI - you might gain 2% fuel mileage and get slightly increased tire wear . That 2% figure is according to tire-company testing. The heaviest legal Toyota RV is going to have around 3800 lbs. on the rear. With four tires that is a max of 950 lbs. per tire. That means the optimum tire pressure for longevity purposes is 20 PSI. Add 20 PSI for a margin of safety and slightly better MPGs and you get 40 PSI. If you want to sacrifice tire longevity and have pressure high enough so one tire can take the weight of two (in case one goes flat) then you inflate even higher. A dually Toyota RV is kind of overbuilt with four truck tires on the back. But it allows one tire to do the work of two in case of a blowout. I run 50 PSI front and back on mine which I consider a good compromise. The front has much less weight on it but also has half as many tires as the rear. Pressure need is pretty much the same. Here are "proper" inflation figures for 185R-14C tires when the only consideration is max life of the tires and the tread hitting the ground evenly and sidewalls flexing as designed. 20 PSI = 1040 lbs, 24 PSI = 1160 PSI, 28 PSI = 1260 lbs., 32 PSI = 1360 lbs., 50 PSI = 1600 lbs, 65 PSI = 1850 lbs. Note these are single tire ratings. Dual tires are usually derated by 10%. A 21 foot Toyota RV loaded to the max (or slightly overloaded) might see 4000 lbs. on the rear (1000 lbs. per tire) and 2000 lbs. on the front (still 1000 lbs. per tire). Four rear tires @ 50 PSI have a load rating of 1440 lbs each which is plenty. My main point is - there is NO one answer to "proper" pressure. It depends on what your main goal is. Quote Link to comment Share on other sites More sharing options...
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