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 > Your search for posts made by 'jadatis' found 11 matches.

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RE: Tow Vehicle Tire Pressure

35 psi is a tipical advice for standard load P-tires. It is the reference- pressure, wich is the pressure for wich the maximum load is calculated for reference-speed of 160kmph/99mph. Carmakers advice it nowadays often and dont calculate it anymore, I think for reasons of responcibility. I once got hold of the European formula to calculate pressure, and went running with it, and now call myself pigheaded Dutch tirepressure specialist. Moast american towing vehicles have large tires with a maximum load that can carry almost the whole gross axle weight rating, so if calxulated , pressure for the P-tire would give about 26 psi. And after the Ford Firestone affaire, carmakers have become scared to advice this. But this means that you dont need to highen up this 35 psi, it already has such reserve, that you can drive a bit overloaded and faster then 99mph.
jadatis 07/17/19 04:03pm Travel Trailers
RE: Tire Pressure-Truck and TT

Only for trailer I calculated. 55 psi is maximum pressure , for 6750lbs , at wich no bumping and maximum reserve and livetime.Assumed Tandem-axle. Assumed tires of TT to be ST-tires , wich are calculated in maxload for 65mph. To get the highest pressure without bumping , I gave the tire a deflection as if the maxload was calculated for 99mph, and assumed 10% on pin, and of axleweight left , I added 11% . Deliberately did not calculate for your given estimated real weight of 6390 lbs , because estimating is always dangerous. But if so could even do with lower. The TV also not calculated because weights estimated even more dangerous.
jadatis 06/30/19 10:51am Travel Trailers
RE: Front tire pressure?

Your cupping is not from low pressure, though that can make it worse. Alignment, bad shockbrakers( already mentioned) and someting loose are the real cources. Even going to wider tires and not compensating that in the alignment, has influence. Even the weightdivision here can havevits influence. Higher pressure then gives less cupping , but your fillings come out if your teeth.
jadatis 06/18/19 07:48am Truck Campers
RE: Front tire pressure?

Answer to above What you give is lineair calculation, and is not bad . Official European calc is ( A/B) ^ 1.25 x 80 = psi. The ^1.25is to the power, like square is ^2, and root is ^0.5. But you dont add 10% first . Wich is for R/L unbalance, but also for pressureloss in time or misreading or inacuracy of pressure device. Then it would give lineair 3190/3420 x 80 = 74,61 psi , so lineair calc comes to about the same as my extra safe calc is 75 psi. Must have missed something , where did you get the 3472 maxload from?
jadatis 06/18/19 07:14am Truck Campers
RE: Front tire pressure?

Filled in in my made motorhome-calculator, it comes to F 41 psi , R 75 psi. Googled your sise tire to be loadindex 123 for single load is maxload 3420 lbs, E- load AT 80 psi. Front that low??!! Yes , search the GAWR's, and you probably discover that rear is already overloaded, and front still have a comfortable reserve. The vehicle-maker calculates for GAWR's ,and for that it probably needs 60 psi. Are these the original sises and loadrange ( E- load / LRE AT 80 PSI) . If the weights are right, and tirespecifications I found too, especially the low front gives better comfort and gripp, but you yust gotten used to the kidney-belt:B My calculator adds 10 % to the given loads( so yoy weighed ? !), and then calculates the pressure with a formula that gives higher pressure then the official European, wich America uses too but only for P-tires since 2006. So my calculation is certainly not to low. Determining the real weights is the most tricky part, in this all, but you weighed fully loaded, so also all the persons? , wich gives you already bonuspoints.
jadatis 06/18/19 05:43am Truck Campers
RE: Max tire pressure and temp setting

If you have sensors screwed on the outside on the valves, the temperature reading cant be trusted, they give something between outside- and inside-tire temp. So the pressure then is the only reliable. But that once you descent from the mountains, and use the brakes to often, the temp in tire can rise to boiling point of water ( 212degrF/100degrC), and with that the pressure rises about 40%. You can not set your TMPS system that high, so then dont be alarmed if the allarm goes off, you the know its a fals alarm, and better concentrate on the driving. Normal use when driving about 50mph at outside temp of 65 degrF, the inside tire rises to about 110-120 degr F, and with that the pressure rises about 10 to 11% . Hottest inside tire temp that is probably still save or tires , so no overheating of rubber , is ( estimated by me) 140 degr F, and it would rise the pressure about a good 15% , but when hotter outside mayby 150degr and more , so when you set it to 15 to 20% upper alarm , I think you are OK. Then when it goes off, and you suspect other factors ( like that descending from mountains or hot outside temp or sun shining on tire)you yourselfes know its a fals alarm and dont be annoyed by the beeps and ignore them. But when only driving that alarm, you probably have a problem. Low alarm can often go off in winter in the morning, because cold temperature outside then same as inside tire , from 65 degr filled goes down about 8% when freesing so 32 degr F outside so inside tire. So low alarm can do with 10% , or less if you also then realise its from cold outside temp, and ignore it. When its colder outside the tire can have lower pressure without overheating the rubber when on higher speed, wich is the goal of advice pressure. Temp differences are larger then, so better cooling down of rubber of tire, wich allows the more heatproduction the more deflection of tire then gives.
jadatis 04/10/19 05:09am Travel Trailers
RE: Tire pressure / dually / TC

RAM 3500 dually that will soon have a TC on it. It's a question of what should the rear tire pressure be and I'm wondering what you run your dually at. The camper should be around 4-5k pounds. I'm planning to install Crossfire Equalization and need a number...psi. RAM said 65 psi Tire manufacture,Nexen Roadian,said 80 psi Both said 80 psi for the front. Who's correct? I can calculate it for you, but need weighed axle-loads , or better axle-end-loads. The estimation you do is verry dangerous. Also need 3 things of tires. 1. Maximum load or loadindex for dual, but give it all so also single. 2. Loadrange or better pressure behind AT . 3. Max speed of tire or speedcode. As long as you dont have weighed loads fully loaded as you go on trip, we will have to use the GAWR's, also give GVWR. And what configuration, drive axle duall we know, but alao TAG axle?
jadatis 03/29/19 10:46am Truck Campers
RE: Max tire pressure

Once read from Tireman9 or Capriracer , that tires have teststandards, so they have to stand a pressure of 2 to 3 times the pressure behind AT. So your 80 psi can rise to 160 to 240 psi before they blow. I would not try this at home, if tire is already damaged by using to low pressure once, so overheating has happened long enaugh, it will blow sooner. But gives an idea that only for the tires, you dont have to be affaid of putting for instance 120 psi in it ,if its undamaged. In old PDF I have from Semperit ( Continental Group) they prescribe 140% of that pressure behind AT( official reference-pressure, but will call it AT-pressure furtheron). Then the tire is allowed 2 times the maximum load when speed zero so standing still. Continental group in Europe gives on many tires 2 pressures. 1. The pressure behind AT but without AT in front of it right behind the service-descriptions ( example 255/70R16 121/119R 65psi) 2 on the other side behind the maxload information "maximum inflation pressure of 10 psi higher then 1 (so then 75 psi). , and this is also cold pressure . Also old documents of Goodyear gave for ST tires a 10psi higher pressure for 75mph. Nowadays, if not given on tire-sidewall, you may not fill cold pressure higher then AT-pressure. In earlyer days it was allowed. Cold pressure is when inside tire airtemp is outside/ambiënt temp, that simple. But sun can heat up the tire inside even when standing still. Also exaust pipe yust in front of rearwheel can make that tire hotter . Cold pressure advice and also AT-pressure is meanth for 18or20degrC/65or68degrF. So you can always argue when filled fi 90 psi on AT80psi tire, that you filled it at freesing point( 0degrC/32degrF), and the pressure has rissen to that 90 psi now its 65 degr F. Suppose you fill at freesing point of 32 degr F your tires with 1,4 times the AT-pressure , and in use the temp in tire goes to boiling point of water so 212 degr F, Then the pressure in tire will rise to a small 2x AT-pressure , so still within the test-standards of 2 to 3 times AT. Boiling point of water it can incidentially get in the tire, when descending the mountains and using the brakes to often. Then heat of brakes is transported trough the rimms to the tire inside. I suspect tiremakers to sometimes fi put a D-load designed tire( AT 65 psi) in the market as E-load ( AT 80 psi) , because especially american market asks for it. But then the 2 to 3 times higher then AT wont go anymore. Mayby thats the reason why they standard dont allow higher then AT-pressure anymore. For P- tires , only maximum cold pressure is given on sidewall, of 44 to 51 psi , and for XL sometimes even 60psi. The AT-pressure of a standardload P-tire is USA system 35 psi always, and EUR system 36 psi with exeptions to lower. XL/reinforced/EXtraload USA 41psi always, EUR 42psi with exeptions to higher and lower. So for P- tires its normal standard to allow higher cold pressure then AT.
jadatis 03/19/19 06:11am Tech Issues
RE: Motor home tire pressure

Hello Everyone, I have a 2001 Monaco Night 36’ DP. My question is about tire pressure. The tires are Goodyear G 661 HAS load range H 255/70 R 22.5 The tires say max. pressure 120# I am not sure what the correct pressure should be. I have not weighed the RV but I have a Cat Scale ticket from the previous owner. He weighted it ready to travel. Full fuel gear and water. The ticket shows a total of 27,140# but 3120# of that is his toad. The front weight was 8640#. The rear was 15,380#. If I understand this right that means each front tire has 4320# on each. The rears (duallys) have 3845# on each of the four tires. The sticker in the coach says to inflate front and rears to 80#. I have looked for an inflation chart on the internet for these tires and have not found an exact match. I have found very similar Goodyears that say the rears should be at 80# and the front at 85#. When I checked the tires, they are at 90#. I would like to lower the pressure a little to help with handling. The RV has the steering box that is not adjustable and has some play in the wheel and wonders a bit at high way speed 60-65 mph. Any insight on correct pressure or where I can find a chart is appreciated. Thanks as always, Lurker Have put weigts of former user in my made extra safe calculator. Gave Front 103 psi so make it 105, and rear 99psi so make it 100. Ofcource new weighing, as suggested, is better, wich you then can use for years, the little variation will be covered by the reserves I put in. Calculator spreadsheet first adds 10% to weighed axleloads, and then calculates with a safer formula then those are used for the official lists, so higher pressure outcome.
jadatis 02/15/19 09:20am Class A Motorhomes
RE: reducing tire pressure when unloaded

To estmate the axleweight in your normal use, find empty weight and give howmany persons and about where. I then will make an estimation and add that much reserve, at wich comfot and gripp is stil accepable. Fuelconsumption will be a bit more with the lower pressures.
jadatis 09/04/18 02:23pm Fifth-Wheels
RE: reducing tire pressure when unloaded

If you an determine weigt on axles, better seperate tires, I an able to calculate a pressure. For normal use often rear can be lower then front, as old biscuit uses. Advice on car is for fully loaded, and rear nowadays even a bit overloaded. Pressure-advice is all for weight and speed.
jadatis 09/04/18 02:03pm Fifth-Wheels
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