tire load range question?

I seperated a tire on the wild cat this last weekend, and after doing some checking the load range D tires (2620#) do not add up to the gvwr. They are 740# short. The tire shop recommended an e range tire capable of 2830#. My gvwr is 11,240 I have the aluminum wheels that are stamped on the inside 3H-139.7 2830lbs and 5H114.3 2150lbs. These e range tires are rated for 80# more than the gvwr. What do the numbers inside my rim mean? and why did my wc come with tires that dont add up to atleast the gvwr? Will my rims hold the 80psi for the new tires?

boyce,

The best advice that I can give you is to go to a reputable tire shop with those numbers and ask the question there. To the best of my knowledge the 114.3 and 139.7 numbers are metric measurements of the distance between the center points of opposing lugs on the wheel. To really be sure, I'd go to my tire dealer and ask.

Hope this helps you.

I believe they figure in the fact that about 20% of the gvwr is carried by the tow vehicle. But I agree with you that they should use higher rated - axles, springs and tires on RV's.
Can not help with your rim psi question.

The tire shop looked at the rim (he showed me the stamps on the inside of the rim) and said it would hold the load and also the 80psi. It is a reputable shop and he hasnt steered me wrong before.

I did not take into account the pin weight. If I subtract that from the gvcw the d rated tires are fine and have 480# to spare. I have 5200# axels so everything is adding up right. Still dont know if the rims can handle the 80psi, other than the numbers on the inside. If they can, would I have better sidewall protection from rocks with the stiffer tires?

if you do the conversion:

139.7mm/25.4mm per inch = 5.5in (probably represents the 6 on 5.5" lug pattern as suggested in the previous. 2830lbs is the weight limit. 2830# is the load limit for a st225/75r15e tire @ 80psi. So I'm guessing they are fine. Here's the inflation table.


114.1/25.4 = 4.5in (probably not applicable in this case. Could be a standard mark should the wheel be bored to a 4 on 4.5" pattern)

I don't know what the 3H and 5H represent.

I agree on RV manufacturers cutting it too close on axle and tire ratings. My Cat came with the 235/80/R16 E rated 80 psi tires that while they are more than rated for the load just seem like a cheap tire. Anyone have LT tires on their rig instead of the ST (special trailer)? Not that I want to load my trailer more but rather would like more load cushion on the tires. I hate being limited to 65 mph with the ST tires.

BayouDude wrote:I hate being limited to 65 mph with the ST tires.

You aren't unless you're loading at the tire's rated capacity. I travel at 70-75mph on some interstates with no issues, but I'm not at 100% of the load rating. My tires are stamped 3250# at 65psi. 4 tires = 13000#. I know I'm only running around at 10500# from the last time I went over the scales. So I could get away with lowering my tire pressure to 55psi and still safely carry the load at 65mph. If you want to travel over 65mph, you need to increase your tire pressure by 10psi cold for every 10mph over 65mph without exceeding the tire's rated pressure. If you're running the st225/75r15d, I'd stick with 65mph max. The WC is just too heavy for them to have that wiggle room.

Here's a link to the article. http://rvtipoftheday.com/rv-trailers/travel-trailer-tire-speed-ratings
Goodyear originally provided the info, but I can't seem to find their article at this moment.

found it....

http://www.goodyear.com/truck/pdf/edb_loads.pdf

page 5 has a handy worksheet.

This is quite interesting to me, I can not find one supplier in the U.K that carries stock of 225 75 15 st tyre. and 16 inch tyres for the load rating I would need also seem to be pretty rare.
One thing I have noticed on this thread is the need to go faster.
Is there no speed limits . In the U.K. any vehicle towing a trailer is not allowed to travel faster than 60 MPH. So my st tyres are OK for over here, but the quality of the tyre could be suspect (made in Tiawan)

Sean

Sean,

There are interstates here in Nevada and the mountain west with speed limits of 75mph. In most of the western states that don't touch the Pacific Ocean, they don't limit trucks or vehicles towing. I've been passed by truck traffic traveling in excess of 75mph on I-80. A lot of these trucks were triples too. If it's flat, straight and traffic is separated, I won't hesitate to travel 75mph if it's posted. Most of the time I running at 65-70mph on the rural highways posted at 65mph. Even in California the towing limit is 55mph, I've passed many CHPs while I was traveling 62-63mph and they didn't seem to care.

For the record, 65-70mph is the sweet spot in my power band that keeps it from hunting between 3rd and OD. The transmission seems to downshift more often if I get below 62mph. At 70mph I'm running around 1950rpms where peak torque occurs.

BayouDude wrote:I agree on RV manufacturers cutting it too close on axle and tire ratings. My Cat came with the 235/80/R16 E rated 80 psi tires that while they are more than rated for the load just seem like a cheap tire. Anyone have LT tires on their rig instead of the ST (special trailer)? Not that I want to load my trailer more but rather would like more load cushion on the tires. I hate being limited to 65 mph with the ST tires.

I work "in the tire business". I got sick and tired of blowing ST tires. I was familiar with the speed rating of ST tires, always watched my speed, and still saw them fail. The manner in which they failed led me to believe that ST tires are a double whammy of poor design and quality. I also hated to keep sending money to competitors (we don't make ST tires).

I just got around to a 16" upgrade - put on Michelin LTX M/S. Ideally I would have liked the XPS Rib but the ltx is no slouch. I'm looking forward to miles of not worrying about tires.

In case anyone is wondering, here are some LT sizes that have equal or greater load rating to the stock st225/75r15:
235/85r16 lrd
225/75r16 lre
245/75r16 lrd
(Because of the Tire & Rim Association standards, you can't just replace the ST with an LT of the same size - the latter has a lower load rating. Long story).

I got a set of 245/75 16, but LRE. They fit but I had to do some fender trimming.

Also, be careful about st E range tires. They're just as susceptible as D tires. Try to find a good name. When I took off the 15"tires, the LRE denmans were showing signs of impending failure. The LRD GY marathon looked fine. Yes I had a mix...

My inlaws just blew a ST225/75r15d tire last Friday. They now have 4 different tire brands on the trailer. This probably the 4th or 5th blowout in 9 years with this particular trailer. In all my years of towing, I've never had a blow out. My FIL is not the most mechanically able being, but I think he has trouble with a tire pressure gauge. I think operator error and neglect is a large part of the problem. I check pressure prior to each trip/day and monitor them visually at stops. Maybe I'm lucky. I don't know.

I am looking at replacing my stock chinese time bombs with some BFG Commercial TA tires. I have the stock 16" LRE on the cat but they sure look cheap. I have had the trailer a little under a year and have put about 5k miles on it.

I went back to the tire shop today and found out the price difference between the d rated and e rated tires and its only $8 a tire. Since my rim is stamped 2830lbs, Im going to go with the e rated tires to, hopefully, run a little cooler on the Arizona hiways and also give alittle more protection from the rocks on the dirt roads I travel.

BayouDude wrote:I am looking at replacing my stock chinese time bombs with some BFG Commercial TA tires. I have the stock 16" LRE on the cat but they sure look cheap. I have had the trailer a little under a year and have put about 5k miles on it.

That's a great tire for the money. I would have done those if I didn't get the ltx m/s.

You should get better service out of those, plus we have real customer care people in the US should you ever have an issue :)

Over 50K miles on my WC, never had a tire problem! I watch the pressure (65psi) and do not run over 65mph if warm outside. Will run up to 70 if cool for a distance. Always check the tire temps when I stop, also the feel the hubs. Replaced tires at 4yrs/40K miles just for my own satisfaction. I can not count the number of trailers I have had pass me going 75-80 and then see them down the road with tire problems.

talala wrote:Over 50K miles on my WC, never had a tire problem! I watch the pressure (65psi) and do not run over 65mph if warm outside. Will run up to 70 if cool for a distance. Always check the tire temps when I stop, also the feel the hubs. Replaced tires at 4yrs/40K miles just for my own satisfaction. I can not count the number of trailers I have had pass me going 75-80 and then see them down the road with tire problems.

I've always taken the same approach. I even bought an IR thermometer and checked tire and hub temps at each stop. I would generally run 60-65 in summer and up to 70 in winter. Knowing what I know I'm very particular with my tires. Yet I managed to have quite a few blow on me. I haven't weighed my rig, but I'm 99% sure I am not overweight (the rig, not me ).

I think STs are ticking time bombs. That's why I went for real tires.
Now I have read about FMVSS139 and the final ruling that the DOT had regarding testing of ST tires - the mfgrs wanted to be opted out but DOT didn't let them. So maybe quality will go up.

Remember, ST tires are available as both Bias Ply and Radial and the Radials will use a bit of a smoother ride.

Most of the tire problems we see are due to under-inflation or overloading. It is becoming increasingly difficult to find U.S. made trailer tires anymore, but many of the LT tires simply don't have the sidewall strength to hold a loaded trailer.

Remember to make sure your tires and wheels are up to the gross loaded weight of the trailer. And make sure they are inflated all the way. This is a different mode of practice that what you would do with vehicle tires which is where a lot of confusion comes.

If the tires have a 2830 pound capacity at 80psi, keep them at 80psi. Drops in pressure drop capacity very rapidly. Check pressure each time you stop. It's a small inconvenience that could prevent a huge inconvenience.

jetskier wrote:found it....

http://www.goodyear.com/truck/pdf/edb_loads.pdf

page 5 has a handy worksheet.

Good find.

Note on page 6, it talks about the prefixes and suffixes to the tire size. If LT is listed as a prefix to the tire size, it should only be used on light trucks. If the LT is a suffix, then the tire can be used on trailers as well.

I am getting a wireless tire pressure monitoring system for the trailer so hopefully I can prevent a blow out.

great topic! Great discussion, thanks to all for the insight! One question and it may be a stupid one. . .

Are there special "Trailer Rims" that one needs to have?

I currently run the stock painted rims and I'm hoping to upgrade to 16" aluminum in the future, what do I look for? If I match the bolt pattern am I OK?

etrailer wrote:

jetskier wrote:found it....

http://www.goodyear.com/truck/pdf/edb_loads.pdf

page 5 has a handy worksheet.

Good find.

Note on page 6, it talks about the prefixes and suffixes to the tire size. If LT is listed as a prefix to the tire size, it should only be used on light trucks. If the LT is a suffix, then the tire can be used on trailers as well.

Not exactly. "LT - identifies a tire primarily for service on light trucks"

A quality LT tire can replace an ST tire of equal load rating just fine.

On the subject of trailer rims, be careful of offset and pressure rating. I think most are 0 offset, make sure the rim can handle the pressure of an e rated tire.

I got my 16" steels from etrailer.com, great price :)

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