jjrbus Posted June 19, 2016 Share Posted June 19, 2016 Out for a ride today, It started so am happy! So took it to the local truckstop to have it weighted. $10.50. It is not completed yet but wanted to see where I am at. Could not weight each individual tire only front and rear axle. The GVWR IIRC is 6000 lbs. steer axle 1880 lb so 940 lb tire Drive axle 3720 930 lb tire Total 5600 lb. The table I was provided with shows that for 185R14 load range D tires I should be running at the lowest pressure of 26 lbs per tire. Hmmmm Quote Link to comment Share on other sites More sharing options...
WME Posted June 19, 2016 Share Posted June 19, 2016 I'll go with the front tires having specd pressure. I always based rear pressure on having 3 tires. That would be near 45 lbs. Handling and the chalk test keep me in the 50-55 lb range Quote Link to comment Share on other sites More sharing options...
zero Posted June 19, 2016 Share Posted June 19, 2016 Running PSI for three tires instead of four makes sense to me. I run 45 PSIG. I have no idea what a "chalk test" is. Quote Link to comment Share on other sites More sharing options...
Derek up North Posted June 19, 2016 Share Posted June 19, 2016 A Load/Inflation Table is NOT a recommendation of what pressure you should run. It is a standard that tire manufactures agree to meet (or exceed). For example, the 1080lb/26psi numbers ONLY mean that the tire can carry the load of 1080lb with a pressure of 26psi. Not the same thing as the pressure for best ride, handling, fuel economy, etc. " I always based rear pressure on having 3 tires." I wouldn't. I'd base it on having 2 tires on 1 end of the axle and 1 tire on the other end. So if you've got a typical 4000lb rear axle weight, you've got (roughly) 2000/side i.e. 2000lb on 1 tire and not 1/3 of 4000lb/tire. Just a little note that the list posted above has a typo in it @ the 51psi point. I'm not sure who typed it up (maybe me!) but 'my' version obtained from Yokohama and Hankook is as follows:- Load Inflation Table - 185R14 - Load Range C & D Inflation (Psi).... 26 ... 29 ... 32 .. 35 .. 38 ... 41 ... 44 .. 47 ... 51 .. 54 .. 58 ... 62 .. 65 Singe (Lb)........... 1080 1147 1213 1279 1345 1400 1466 1532 1599 1665 1731 1786 1874 Dual (Lb)............. 1036 1102 1158 1223 1279 1334 1389 1455 1521 1588 1643 1709 1764 Quote Link to comment Share on other sites More sharing options...
jjrbus Posted June 19, 2016 Author Share Posted June 19, 2016 7 minutes ago, Derek up North said: A Load/Inflation Table is NOT a recommendation of what pressure you should run. It is a standard that tire manufactures agree to meet (or exceed). For example, the 1080lb/26psi numbers ONLY mean that the tire can carry the load of 1080lb with a pressure of 26psi. Not the same thing as the pressure for best ride, handling, fuel economy, etc. " I always based rear pressure on having 3 tires." I wouldn't. I'd base it on having 2 tires on 1 end of the axle and 1 tire on the other end. So if you've got a typical 4000lb rear axle weight, you've got (roughly) 2000/side i.e. 2000lb on 1 tire and not 1/3 of 4000lb/tire. Just a little note that the list posted above has a typo in it @ the 51psi point. I'm not sure who typed it up (maybe me!) but 'my' version obtained from Yokohama and Hankook is as follows:- Load Inflation Table - 185R14 - Load Range C & D Inflation (Psi).... 26 ... 29 ... 32 .. 35 .. 38 ... 41 ... 44 .. 47 ... 51 .. 54 .. 58 ... 62 .. 65 Singe (Lb)........... 1080 1147 1213 1279 1345 1400 1466 1532 1599 1665 1731 1786 1874 Dual (Lb)............. 1036 1102 1158 1223 1279 1334 1389 1455 1521 1588 1643 1709 1764 Quote Link to comment Share on other sites More sharing options...
zero Posted June 19, 2016 Share Posted June 19, 2016 I fail to see whey so many here seem to like Toyota engineering, but think their PSIG recommendations for maximum payload trucks are wrong. I DO understand wanting some redundancy in case of having a flat and having to drive on only three tires instead of four. That makes 45 PSIG just fine. Quote Link to comment Share on other sites More sharing options...
zero Posted June 19, 2016 Share Posted June 19, 2016 I know my posts are redundant, but so is this discussion. Toyota recommended 29 PSIG with max load in 1988 for the rear duallies, and in 1990 upped it to 32 PSIG. Note that is for max load, and not for some empty minitruck. Quote Link to comment Share on other sites More sharing options...
DanAatTheCape Posted June 19, 2016 Share Posted June 19, 2016 I suspect that the document you keep posting was in great error and has probably been rescinded. The numbers on the tire show rated max rates on tire at various inflation rates. Given how heavy these campers are, I think anyone would have to be crazy NOT to be at or near max rated PSI on the rear tires. For those who think that they can run at low ratings, consider that if one tire fails, it's mate will be right behind. This sort of low pressure "logic" is crazy! What is the worse case scenario? - one tire fails while performing an extreme maneuver and the other has to carry all the load. I currently have class D hankook on mine . Even with max psi - 65 - my tires appear low - these campers are indeed heavy - unloaded, and they are heavy all the time. Quote Link to comment Share on other sites More sharing options...
Derek up North Posted June 19, 2016 Share Posted June 19, 2016 2 hours ago, DanAatTheCape said: I suspect that the document you keep posting was in great error and has probably been rescinded. IF the 1988 recommendations (29psi) was 'in great error', then I guess the 1990 recommendation should (reasonably) be considered the 'correction' you're looking for. The bottom line is that you/we are all free to run whatever pressure we choose and that as long as you're somewhere between the minimum (per the L/I tables) and the maximum (50 or 65 psi) you should be 'good', whatever logic you choose to apply. Quote Link to comment Share on other sites More sharing options...
Derek up North Posted June 19, 2016 Share Posted June 19, 2016 4 hours ago, jdemaris said: I have no idea what a "chalk test" is. https://www.google.ca/search?q="chalk+test"&ie=utf-8&oe=utf-8&gws_rd=cr&ei=1MtmV6TbDeWCjwT8mJaYCA Quote Link to comment Share on other sites More sharing options...
zero Posted June 19, 2016 Share Posted June 19, 2016 6 hours ago, DanAatTheCape said: I suspect that the document you keep posting was in great error and has probably been rescinded. Oh come on ! Same basic figures every year up through 1994 in all those official manuals. Note those figures from Toyota agree with the load-tables that Derek posted. Not very complicated math. Quote Link to comment Share on other sites More sharing options...
jjrbus Posted June 19, 2016 Author Share Posted June 19, 2016 8 hours ago, jdemaris said: I know my posts are redundant, but so is this discussion. Toyota recommended 29 PSIG with max load in 1988 for the rear duallies, and in 1990 upped it to 32 PSIG. Note that is for max load, and not for some empty minitruck. I find it interesting that for single rear axle 8 ply tires are speced and for dual rear axle 6 ply tires are speced. In my very limited experience with heavy vehicles I was taught to follow the load and inflation tables. That proper tire inflation was not based on intuition, speculation or looks or feels right but on science and engineering. I was pointed in this direction by people with impressive credentials whom I trust. In reading about this under inflated tires are dangerous and over inflated tires while not as highly reported can be dangerous. Not knowing what the pressure should be I have driven my Toy with 65 lbs all around and I do not like the way it rides, handles or responds. Quote Link to comment Share on other sites More sharing options...
zero Posted June 20, 2016 Share Posted June 20, 2016 Tire companies design, and test a radial tire - and then sell it with an intention it will be used with the proper "loaded radius." In plain English, that "planned squatting" of a tire. NOT supposed to be round. People who complain about this squatting and try to hike up the inflation to defeat it, are also defeating what was intended for that tire as far as handling and longevity goes. Does it hurt anything by running the tires at the max pressure marked on the sidewalls? No. It probably has a negative effect on ride and long-term wear, that's all. Running at the recommended lower PSIG also hurts nothing and also gives the tires the best shot of performing as designed. Now - if your Toyota is already overloaded and beyond the design-limits of the truck - then who the heck cares? Do what you want. That all said, Toyota clearly knew what they were doing with their tire recommendations and 29-32 PSIG is dead-on for the rear on a truck with the absolute maximum payload. Again, if it is 1000 lbs. over what Toyota allows - then we are not talking about Toyota making "mistakes" in their tech manuals, are we? I'll add that if a coach-builder created an RV and knew it would be used well over the design limits that Toyota allowed - again - Toyota figures have little to do with this. Quote Link to comment Share on other sites More sharing options...
jjrbus Posted June 20, 2016 Author Share Posted June 20, 2016 Does it hurt anything by running the tires at the max pressure marked on the sidewalls? No Running at max or over inflated? Everything that I read for a tire that is over inflated says that it is not a good idea. That it affects braking and handling, that tires are more easily damaged and increases the risk of hydroplaning! Also increases wear in the middle of tire, but for me that is not an issue. Hitting the brakes in a wet curve might be the perfect recipe for disaster with over inflated tires. Quote Link to comment Share on other sites More sharing options...
zero Posted June 20, 2016 Share Posted June 20, 2016 Yes, premature wear IS an issue when running pressures too high. My point, at it relates to our Toyotas is this. Many of us do not drive enough to ever see that premature wear. At least the way I use RVs, I wind up getting dryrot cracks in the tires first and wind up replacing long before they wear out. I pulled off a set of Firestones from my rig two years ago and the tread looked near like new. Full of cracks and I suspect they were over 20 years old. Too old to have 4-digit DOT dating codes. My rear tires on my 1988 dually Minicruiser - for absolute best ride and wear - should be around 32 PSI. I run 45 PSI. I call that a compromise since I like the idea if I get a flat, the remaining 3 tires can still bear the weight. Just my personal choice. I DO have a spare so in a way, it is kind of silly. Many of the companies that made this motorhome coaches also upped the PSIG recommendations above what Toyota did. I'm sure because they knew d*mn well they would be used exceeding the Toyota design limits. Quote Link to comment Share on other sites More sharing options...
zero Posted June 20, 2016 Share Posted June 20, 2016 I wish I could read all this recertification-label. It is from a 1987 Toyota dual-wheel box-truck. 22RE, auto trans, and full-floating rear. It was officially recertified for GVWR and tire pressure recommendations but cannot make out the label for tire pressure. I think it read 41 PSI in the rear, but am not sure. GVWR is 5500 lbs. Gross rear axled weight rating (GAWR) is 2780 lbs. Tire size is R14C. The truck only had car tires on it anyway. 185/75-R14" Quote Link to comment Share on other sites More sharing options...
jjrbus Posted June 20, 2016 Author Share Posted June 20, 2016 I do not think it is silly, there is always the possibility of getting a flat where there is no place to safely pull over. Ruining the remaining tire in the process. Possibility? No it is in the laws of life it will also be raining/snowing and just miserable out! Plus with a slow leak we may be driving for many miles with one tire carrying the load! Jim Quote Link to comment Share on other sites More sharing options...
Derek up North Posted June 20, 2016 Share Posted June 20, 2016 1 hour ago, jjrbus said: Plus with a slow leak we may be driving for many miles with one tire carrying the load! Jim Thank God they invented these! http://www.ebay.com/itm/Solar-Power-Wireless-TPMS-Tire-Pressure-With-LCD-Monitoring-System-4-Sensors-/201462339646 Quote Link to comment Share on other sites More sharing options...
Back East Don Posted June 20, 2016 Share Posted June 20, 2016 38 minutes ago, Derek up North said: Thank God they invented these! Just when I thought it was safe to drive again, what do I do the the leftover two tires? Quote Link to comment Share on other sites More sharing options...
Derek up North Posted June 20, 2016 Share Posted June 20, 2016 You put all 4 on the rear tires and just watch the front ones just like normal. Or spend the extra bucks and buy a 6 sensor kit. Quote Link to comment Share on other sites More sharing options...
Wade Posted June 20, 2016 Share Posted June 20, 2016 On 6/19/2016 at 8:41 AM, jdemaris said: I fail to see whey so many here seem to like Toyota engineering, but think their PSIG recommendations for maximum payload trucks are wrong. I DO understand wanting some redundancy in case of having a flat and having to drive on only three tires instead of four. That makes 45 PSIG just fine. I can't speak for anyone else but for me, I do respect Toyota engineering. However, there are a multitude of reasons that I choose to run a higher pressure than what was in my owners manual. For one thing, there is little likelihood that an engineer in 1985 would have the data to recommend the ideal pressure for a tire manufactured in 2015. Tires have changed a lot in 30 years! I am glad that you brought this whole tread up Jim. I will do more experimenting and will likely run a bit lower than I would have before. Currently the tire shop set my tires to sidewall max. I am pretty satisfied with the way the truck handles but as this is my first Toyota MH, my expectations may be way off and it will be interesting to see how things change as I make different adjustments and hopefully some day actually have it loaded for a boondocking trip;-) One thing that I know I will do is monitor the tires with my IR gun. As it sits now, nearly empty with tires at the max, a 20 min 60mph run followed by a couple of miles of city streets to get to my house, resulted in even temps across all tires and just a few degrees above ambient. My owners manual states that the fronts should be in the 20s. If I ever were to drop that low it would be interesting to see how much additional heat would be generated. I am definitely going to lower them significantly from where they are now and see what happens. I also hope to take gas mileage into account. Unfortunately that is one more of my many projects to complete. I was going to fill the tank so I could check mpg when the pump kicked off on over-flow there was gas dripping from below. The tank is all covered in sheet metal so I don't know if it is a return hose or a leak in the tank. I do know that when I got home the leaking has stopped and I have about 3/4 of a tank on the gauge. Don't have a clue as to how accurate the gauge is. I do know that with highly inflated tires I am amazed at what my gas mileage appears to be anyway. The gauge was flat on E when I put 5 gal in. Drove it for about 50 miles mixed city highway and gauge was still more than an eighth. Put another 5 gal in it and drove it about another 30 miles or so and about 6.5 gal cause the shut off and left me with 3/4 of a tank. Wade Quote Link to comment Share on other sites More sharing options...
Derek up North Posted June 20, 2016 Share Posted June 20, 2016 I've never had a gas gauge in any vehicle that I'd describe as anywhere near accurate or linear. Quote Link to comment Share on other sites More sharing options...
jjrbus Posted June 20, 2016 Author Share Posted June 20, 2016 A long time ago I bought a large motorhome and decided that I would not tract mileage as I did not want to know. If I knew how bad it actually was I likely would have never drove it! It will be difficult to do with the Toyota with such a small tank, but I really do not want to know. With the low mileage driven by most RV owners MPG should have nothing to do with tire inflation. Where decent ride, good handling and safety should be the main concerns. Most RV's have the aerodynamics of a brick and very unlikely that inflating a tire to max pressure would increase MPG by 10% or more. Quote Link to comment Share on other sites More sharing options...
Wade Posted June 20, 2016 Share Posted June 20, 2016 I guess the mpg thing is kind of an ego thing for me;-) I like to have the engine and drive train as tip top as I can. On the deflated ego front, the mpg of the Toyota over the mpg on my old Dodge should mean the ability to use it for more or longer trips. Unfortunately there are too many times where I just don't have the $ to absorb the lower mpg. I just noticed the door sticker from the coach manufacturer and they spec all tires, single in front and dual in back, at 65psi cold. Wasn't expecting to see that. Wade Quote Link to comment Share on other sites More sharing options...
jjrbus Posted June 21, 2016 Author Share Posted June 21, 2016 10 hours ago, Derek up North said: Thank God they invented these! http://www.ebay.com/itm/Solar-Power-Wireless-TPMS-Tire-Pressure-With-LCD-Monitoring-System-4-Sensors-/201462339646 I have posted on a couple forums looking for input on the cheap setups, lots of feed back on the high end big dollar stuff but zero on the cheapies. Quote Link to comment Share on other sites More sharing options...
jjrbus Posted June 21, 2016 Author Share Posted June 21, 2016 4 hours ago, Wade said: I guess the mpg thing is kind of an ego thing for me;-) I like to have the engine and drive train as tip top as I can. On the deflated ego front, the mpg of the Toyota over the mpg on my old Dodge should mean the ability to use it for more or longer trips. Unfortunately there are too many times where I just don't have the $ to absorb the lower mpg. I just noticed the door sticker from the coach manufacturer and they spec all tires, single in front and dual in back, at 65psi cold. Wasn't expecting to see that. Wade I do not put much faith in anything the Rv industry does or says. Jim Quote Link to comment Share on other sites More sharing options...
jjrbus Posted June 21, 2016 Author Share Posted June 21, 2016 20 hours ago, Derek up North said: Thank God they invented these! http://www.ebay.com/itm/Solar-Power-Wireless-TPMS-Tire-Pressure-With-LCD-Monitoring-System-4-Sensors-/201462339646 I started looking at these online and see what may be an issue, there are 2 tools used to install some of them which may be a nuisance when trying to add air to the inner duals. Has anyone used these on the duals or see a work around? https://www.youtube.com/watch?v=sF3OHTzXIXs Quote Link to comment Share on other sites More sharing options...
zero Posted June 21, 2016 Share Posted June 21, 2016 On 6/19/2016 at 0:42 PM, Derek up North said: IF the 1988 recommendations (29psi) was 'in great error', then I guess the 1990 recommendation should (reasonably) be considered the 'correction' you're looking for. The bottom line is that you/we are all free to run whatever pressure we choose and that as long as you're somewhere between the minimum (per the L/I tables) and the maximum (50 or 65 psi) you should be 'good', whatever logic you choose to apply. One comment on all that. 1988 Toyota had a max weight rating of 5500 lbs. and thus the 29 PSIG for the rear. 1990 the max weight rating was raised to 6000 lbs. and that is why pressure was raised to 32 PSIG for the dually rear. Quote Link to comment Share on other sites More sharing options...
Maineah Posted June 21, 2016 Share Posted June 21, 2016 Coach manufactures sticker on mine said 50 all around! Quote Link to comment Share on other sites More sharing options...
jjrbus Posted June 21, 2016 Author Share Posted June 21, 2016 (edited) So instead of getting anything done I am surfing. I am starting to lean towards the CARCHET system. They have favorible reviews, owner can replace batteries in sending units, displays pressure or temp and tools look like they might work with rear duals. They also have replacement sensors available. Also available for 6 tires, but I do nt really want to spend $200 so will buy the 4 tire setup and only monitor the duals. https://www.amazon.com/CARCHET-Pressure-Monitoring-Trailer-External/dp/B01H3KPZSQ/ref=sr_1_6?s=automotive&ie=UTF8&qid=1466523414&sr=1-6&keywords=tire+pressure+monitoring+system&refinements=p_89%3ACARCHET https://www.amazon.com/CARCHET-Pressure-Monitoring-Intelligent-External/dp/B012AEEYDM/ref=sr_1_1?s=automotive&ie=UTF8&qid=1466523695&sr=1-1&keywords=tire+pressure+monitoring+system&refinements=p_89%3ACARCHET There is one more configuration but I cannot find it at the moment, it is a simple monitor that plugs into the cigarette lighter. I guess they do not call them cigarette lighters anymore. Here is the simple one, same price. https://www.amazon.com/CARCHET-Pressure-Monitoring-Intelligent-External/dp/B012AEEYDM/ref=sr_1_1?s=automotive&ie=UTF8&qid=1466523695&sr=1-1&keywords=tire+pressure+monitoring+system&refinements=p_89%3ACARCHET Edited June 21, 2016 by jjrbus Quote Link to comment Share on other sites More sharing options...
Wade Posted June 21, 2016 Share Posted June 21, 2016 15 hours ago, jjrbus said: I do not put much faith in anything the Rv industry does or says. Jim Jim, I get that. However, I am reasonably certain that the Toyota engineers who came up with the PSI ratings did not run their calcs with a Cube that extends 21 feet and is over 8 feet high attached to the chassis. The torsional load that such a huge cube must excerpt on the tires is likely significant. Wind, cornering, and braking, would tend to have the effects on the sidewalls amplified by the shear size of that cube compared to the overwhelming production of trucks that the calcs were likely based on. Likely the coachmakers just pulled the numbers out of a hat because they knew that what they were doing was going to have an effect beyond what Toyota originally designed for. Wade Quote Link to comment Share on other sites More sharing options...
jjrbus Posted June 21, 2016 Author Share Posted June 21, 2016 I have little faith in the RV industry, if they told me it was an 8 cyl auto, I would count the spark plugs and look for a clutch! The info that JD posted seems to indicate that Toyota took RV's into consideration. Quote Link to comment Share on other sites More sharing options...
davidtan Posted June 21, 2016 Share Posted June 21, 2016 Will these tire sensor caps from Auto zone work ? Quote Link to comment Share on other sites More sharing options...
jjrbus Posted June 21, 2016 Author Share Posted June 21, 2016 I had some valve extensions on my previous motor home and they leaked and almost ruined a $400 dollar tire, I threw them out! So no more extensions for me. Then I saw the tire sensor caps that change color and thought what a great idea! So I bought a set and put them on my Ford Windstar. I was driving through Punta Gorda FL when another driver indicated to me that something was wrong towards the rear of my van.. I pulled over and look and the right rear tire was almost flat. The cap on that tire had sprung a leak. I only had them a short time so returned them and got my money back. There is a higher probability the monitoring systems might tell me if something is wrong. Jim PS the cap that leaked did show red by the way. Quote Link to comment Share on other sites More sharing options...
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