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About TireHobby

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  • Birthday 01/21/1939

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  1. TireHobby

    Newmar fifth wheel tire and wheel dilemma

    I don't think anyone has mentioned height & width requirements for the replacement tires. Very important with dual assembly fitments. Wheels/rims do not require markings for their weight and psi ratings. OEM providers normally require such markings from the manufacturers. Some rims will be limited by weight and PSI restrictions. Others will just be limited by weight restrictions. Those may be inflated to whatever PSI is required for them to provide their maximum load capacity. The only way to get a valid answer about wheels not marked is to ask the wheel manufacturer. They are required to provide such information. You should also validate any wheel off-set. Almost all trailer wheel fitments require zero off-set. Remember to use the derated dual fitment load values for the replacement tires. Tires without a dual rating should not be used.
  2. TireHobby

    New RV tire changeover ?

    Tireman9 has asked similar questions on all forums where he is a member, commercial or otherwise. He normally does not specify if the changeover is for a new or used trailer. The rules are different. 1. Did you ask/request the tires be changed? 2. If yes, did you change brand or size or both? On a new trailer the dealer is allowed to change brands but not the size or design unless the trailer manufacturer authorizes the change with published options. 3. About how much were you charged? 4. If you asked, did any dealer you were shopping at refuse to do a changeover? For new trailers there is a rule that states, in part, that the tires on the trailer at the time of first sale MUST be the same size as those shown on the vehicle certification label. For the dealer to change sizes a new certification label would be required. It must be approved by the vehicle manufacturer. The dealer is in a catch 22. I doubt they would sell a trailer with a fraudulent federal certification label. For sellers of used trailers the above rule does not apply. However, tire industry standards require replacement tires to have a load capacity equal to or greater than the OE tires. When the certification label has the tires designated size, such as, ST225/75R15, the ST is part of the tire’s official size. Replacing the ST with a LT or P would be considered a major deviation in tire design and considered a misapplication. UNLESS, the replacement is approved by the vehicle manufacturer. Good luck with that one.
  3. TireHobby

    Axle spacing on Heartland 4100 King.

    A lot of 5th wheel trailers with OE tire size ST235/80R16, regardless of brand, have a standard 32" spacing between axles. Get a tape measure and check from center to center on both sides. If actually 32" the ST235/85R16 tires are probably to tall. https://tiresize.com/calculator/
  4. Here are the specs for the steel cased Sailuns.....http://www.sailuntires.ca/PLT/S637st.html Note: The GY G614 (LT235/85R16G IS a trailer tire. That's what the RST on it's sidewall is telling you, Regional Service Trailer.
  5. That's probably because they have quit building them. They now have two steel cased ST tires that have replaced the LT (RSTs). They are in sizes ST235/80R16 LRG rated at 4080# @ 110 PSI and, ST235/85R16 LRG rated at 4400# @ 110 PSI.
  6. TireHobby


    In RV trailer model years 2005 - 2007 a great many of their manufacturers selected the LT235/85R16E tires for Original Equipment fitments on 6000# GAWR axles. Their load capacities - 3042# @ 80 PSI - needed very close monitoring to insure they were always inflated to the 80 PSI. Many owners found that the heavy duty steel cased tires were much more durable for replacements. Those brands were Michelin & Bridgestone. It’s the trailer manufacturer’s prerogative to select whatever tires they deem appropriate for OE fitments. Once certified to the vehicle they become the benchmark. Many ST tire manufacturer's are building like sized tires sized ST235/85R16E. Their physical dimensions are very similar to the LT tires. However, their load capacity is much higher at 3640# @ 80 PSI. Almost all ST name brands provide them.
  7. TireHobby

    Tire Question

    Continental builds a 225/75R16 European designed tire with a Vanco brand in load range E rated at 3195# @ 83 PSI (121/120R E). It’s a highway all-season radial and very popular on class B and smaller class C RVs. General also builds the same tire with those specs.
  8. Are the tires the same size as what is recommended on the tire placard or certification label? How old are they? Here is a picture of what can happen to a tire that has a tread separation but not yet lost the tread. Both of the tires in the picture have the same size designation and are from the same manufacturer. It's amazing how much larger a tire can get before it throws the tread. http://www.irv2.com/photopost/showfull.php?photo=27625 On Edit: The distance between tires is normally a question the axle manufacturer can answer. Dexter says for their axles the minimum is 1".
  9. TireHobby

    Tire Pressures

    Motor Home owners seem to always give information on this subject that is intended for vehicles governed by different regulations. If your MHs federal certification label has recommended cold inflation pressures on it, the standards for maintaining them will come from FMVSS standards. Under FMVSS standards tire manufacturers do not set vehicle tire inflation pressures, vehicle manufacturers do. It's a standards requirement. In chapter 4 provided below you will find the correct procedures. Read the whole thing. Reading til you find what you're looking for may be out of context and you'll be right back where you started from. http://www.mcgeecompany.com/wp-content/uploads/2010/12/complete-manual.pdf For those that won't take the time to read the document I'll add this. It's an industry wide standard to NEVER use less tire inflation pressure than what has been recommended on the vehicle's certification label, tire placard or in the vehicle owner's manual.
  10. TireHobby

    New 5er - New Hitch - New Tires?

    Your trailer's axles probably have a GAWR on the certification label/tire placard of 6000# per axle. The OEM tires, when serviced to 80 PSI will provide nearly 18 percent of load capacity above the maximum load for that trailer. That's a far better reserve load capacity than many other models are equipped with. Depending on usage - your call - they are good for 3-5 years. Trailer tires are not mileage tires. OEM Westlake tires are provided to the vehicle manufacturers serviced with 100% nitrogen (green valve cap). That's good for new trailers because it pretty much assures there is no water vapor in the tires.
  11. TireHobby

    Tire Choices

    Were the OEM tires 17.5"?
  12. TireHobby

    trailer tires and tow speeds

    Tire industry standards are very consistent. Here is something about them by Michelin. http://www.michelinman.com/US/en/help/how-to-choose-tires.html#tab-4
  13. TireHobby

    trailer tires and tow speeds

    There are a lot of different brand name manufacturers building 16" trailer tires with load capacities from 3420# to 4080# In load ranges E, F & G. Some are ST235/80 R16 and others are ST235/85R16. The ST235/80R16E has three load capacities, 3420#, 3500# & 3520#, all at 80 PSI. Read the specs or sidewall info before you by them. The ST235/85R16E has a load capacity of 3640# at 80 PSI. The ST235/85R16F has a load capacity of 3960# at 95 PSI. The ST235/80 R16G has a load capacity of 4080# at 110 PSI. There are some - what I call hybrid LT trailer tires - 16" LT trailer tires size LT235/85R16G rated at 3750# at 110 PSI. They are called RST (regional service trailer) and will have that information on their sidewalls. Happy hunting.
  14. TireHobby

    trailer tires and tow speeds

    Special Trailer tires (ST) without any speed markings on their sidewalls have a maximum speed rating of 65 MPH. Manufacturers of ST tires are in the process of identifying their tires with an official speed letter or actually molding the speed restriction into the tire’s sidewall. There is no speed letter for 65 MPH. Speed letter K is for 68 MPH but seldom used. The speed letters follow a tire service description displayed on the tire‘s sidewall. A typical service description may look like this, 117/112N, the N is the speed rating and it is 87 MPH. Replacement tires for RV trailers are a complicated proposition. The only official recommendations an owner can get is from the trailer manufacturer. Hardly anyone likes that idea so the internet forums are loaded with misinformation. The best thing an owner can do is find a tire manufacturer like Bridgestone/Firestone that publishes their tire industry standards for replacement tires in a PDF on the internet. I used that name because (IMO) their’s is the easiest to figure out for trailer tires (any design).
  15. TireHobby

    Tire size

    The difference in the overall width of the 85 tires are not normally going to present a fitment problem. However, most large RV trailers will have triple axle spacing very close to one another and the larger diameter of the 85 tires could cause them to be to close to each other. You could ask the specific axle manufacturer what the minimum clearance requirements are. Dexter says 1”.