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Post by bigbill on Sept 13, 2017 14:31:10 GMT -8
Just a simple explanation of tire markings. on the side of your tire you will find the brand name followed by a series of letters and numbers. Example P215/65R15 95H M&S P=PASSENGER CAR USE (DO NOT USE ON TRAILERS). 215 = NOMINAL WIDTH OF TIRE IN MILLIMETERS. /65 is Aspect ratio (height to width). R= radial. 15 = rim diameter. 95H = load index and max speed symbol (contact your tire dealer to have decoded). M+S indicates this tire has some mud & snow capabilities ALL TRAILER TIRES MUST BE MARKED WITH LT OR ST (LT MEANS LIGHT TRUCK OR TRAILER ST MEANS TRAILER USE ONLY). Some tires will show their max load rating in small letters next to the wheel This is the max load if inflated to the listed max air pressure, as air pressure drops this figure drops dramatically. The DOT number found in next to the wheel indicates it meets federal standards, the next two numbers are the plant code where manufactured, the last four numbers tell when it was built such as 3197 means the 31st week of 1997. If tire has a heat code A is highest B is next then C each is a lower heat rating so if comparing two tires and everything was the same except the heat letter A would be the best. Older tires will be marked differently. Tires older than four years should be replaced. Hope this information proves useful.
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jardin
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Post by jardin on Sept 14, 2017 6:20:07 GMT -8
Thanks for this bigbill.
You filled in a couple gaps I was missing in the codes. I greatly appreciate the wisdom that you contribute here.
I feel like tires are overlooked by most folks and we all know things can get squirrely quick with the wrong tires. Just because I come across it all the time and I do not think it can be said enough.
PLEASE DO NOT USE P TIRES ON YOUR TRAILER FOLKS.
It is dangerous
BTW I have not heard of it being ok to use LT tires. I take it that the sidewalls are stiff enough. You would know more than me.
Thanks again
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Post by bigbill on Sept 14, 2017 18:26:07 GMT -8
The feds say it is safe to use LTs on trailers but don't use STs on a truck.
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roadtripper
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Post by roadtripper on Sept 14, 2017 19:41:40 GMT -8
Thanks and great post. It should be marked to stay up front for reference and all to see. My local tire guy of many years has convinced me to stick with trailer tires.
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jardin
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Post by jardin on Sept 15, 2017 5:31:28 GMT -8
So I just went out to look at the age of the tires on the trailer I bought in May....Been wondering how old they are My DOT code reads:
DOT 7DJT 1ET
Does this mean anything to you guys?
if I cannot figure it out my policy is to just buy new tires...
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Post by bigbill on Sept 15, 2017 5:36:52 GMT -8
A trailer tire is designed for a trailer. So I think that is the best option, but the LTs meet fed specs for trailers also and if I needed a tire or tires in an area where STs were not available without waiting for them to be special ordered (like a Sunday afternoon on my way home or in the middle of a vacation) I would use LTs.
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Post by bigbill on Sept 15, 2017 14:00:07 GMT -8
So I just went out to look at the age of the tires on the trailer I bought in May....Been wondering how old they are My DOT code reads: DOT 7DJT 1ET Does this mean anything to you guys? if I cannot figure it out my policy is to just buy new tires... You don't have enough numbers, according to current description there should be four numbers at the end, the first two of those is the week and the last two are the year. Also check for a small round brand that shows mfg date. They may have been mfg before the change in coding. Check with your tire store.
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mobiltec
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Post by mobiltec on Sept 27, 2017 17:27:48 GMT -8
Tires have shelf life.... Tires should be replaced after five years of use. Even if the trailer never moved an inch. I use ONLY tires that are marked Trailer Tires. They cost more but repairs to the trailer when you have a blow out will cost way more than the tires.
Thanks for posting this Bill.
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datac
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Post by datac on Sept 28, 2017 10:34:05 GMT -8
If your tires are old enough that the DOT date code doesn't decode the way you think it should, stop what you're doing and ditch them. It doesn't matter what they look like or how much tread they have left. As others have said, five years should be considered their expiration date.
Besides stories of mayhem from old tires (of which there's no shortage), I had an eye-opener a few years back. I'd grenaded the freshly-built engine in a '65 Mustang, and decided to do the bodywork and paint while I had the engine out. I'd completely rebuilt the suspension some time earlier with all of the good performance stuff, autocrossed it a few times, and had brand new (and expensive) performance tires on it.
Well, between parenthood, job, and 90-year old house, it took about nine years before the car was back on the road again (ended up with a full-blown restoration thanks to scope creep). I knew I'd need to replace the 9-year old tires, but I drove it easy around town for a few days while I broke the engine in and shook the bugs out. My first impression was that I'd gotten a lot older in those nine years, and had maybe outgrown the super-stiff competition suspension I'd put in. I started shopping for softer springs and shocks, thought I might ditch the urethane bushings for stock rubber, etc., etc., since it was beating me up to the point that it wasn't enjoyable to drive.
You guessed it. New tires went on, and it was like night and day- firm but supple and smooth, just like I remembered. The compound in the old tires had hardened to the point that they were beating me to pieces, despite the fact that they still looked like new.
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Post by bigbill on Sept 28, 2017 14:23:50 GMT -8
The new Federal standard as I understand it is discard after four years not five. I have to admit that I have towed with tires older than five years but I have also seen very serious wrecks caused by tires that looked like new failing. The question we each have to answer is , WHAT IS YOUR SPOUSE AND CHILDREN'S LIFE WORTH PLUS YOUR OWN. I have seen trailers flip large trucks let alone what they can do to a small SUV or car. Also when buying new tires please do two things 1. Check date of mfg to make sure they haven't been setting in a warehouse for years. 2. check the price of a higher load rated tire than what you are considering you may find the extra margin is only a very few dollars more. Many people who have tire troubles often are buying to light of a tire. I personally like tires that are rated for twice my expected load, as I don't like tire failures.
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turbodaddy
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Post by turbodaddy on Sept 28, 2017 18:10:09 GMT -8
This is all really great info, thanks to all. I'd just like to emphasize that most trailer tires are rated for 65mph MAX. Can't tell you how many times I've been passed by people towing at much higher speed. Also, many C-list ads say things like "good rubber" or "original tires look great". Don't be mislead. Good idea to carry a full size spare (if you can) while travelling. Practice changing out a flat at home in the safety of your driveway, just so you'll know what to expect. You really need to think it through, and have a plan because it is much more difficult than just changing a tire on a car. I carry two hydraulic jacks and several different thickness blocks of wood to be sure I'll be able to lift the camper high enough to remove the flat. The upside is that even if you are way out in the boonies in some place like New Mexico, 50 miles away from the nearest town...you have a place to sleep, cook, and rest until you can change it out or help is on the way.
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turbodaddy
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Post by turbodaddy on Sept 28, 2017 18:26:03 GMT -8
Sorry, I meant to add this. An often overlooked item is the tow vehicle's spare tire. The tire itself may be OK, but might not be properly inflated. On many vehicles the mechanism holding the spare underneath becomes so corroded that it is impossible to release the spare. I've heard of people being able to lower the spare, but then not being able to actually get it off of the vehicle, leaving the (80 lbs plus) spare swinging underneath the vehicle. Imagine what a bummer it would be to go through all the misery of trying to release the spare only to find that it isn't usable. Best to check all this out before leaving home.
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jardin
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Post by jardin on Sept 29, 2017 4:43:21 GMT -8
Thought I would report back that when I was under the rig last week, working on getting her ready for the maiden voyage I crawled under and sure enough saw that the DOT code was on the inside wall of the tire...manufactured in 07 Needless to say I just got a new set and will be having the mounted today.
Unfortunately it does not help that tire dealers are not as helpful or knowledgeable either. I was calling around asking about manufacture dates getting answers like.... "I cannot tell you the age of the tires we will send you as we have warehouses all over the country" "according to federal law we can sell tires as "new" that are 5 years or less from manufacture date" "Trailer tires are good for at least 10 years"
These are the folks who are supposed to help those who do not know.
Anyway thanks again for posting this.
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mobiltec
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Post by mobiltec on Sept 29, 2017 6:23:42 GMT -8
Thought I would report back that when I was under the rig last week, working on getting her ready for the maiden voyage I crawled under and sure enough saw that the DOT code was on the inside wall of the tire...manufactured in 07 Needless to say I just got a new set and will be having the mounted today. Unfortunately it does not help that tire dealers are not as helpful or knowledgeable either. I was calling around asking about manufacture dates getting answers like.... "I cannot tell you the age of the tires we will send you as we have warehouses all over the country" "according to federal law we can sell tires as "new" that are 5 years or less from manufacture date" "Trailer tires are good for at least 10 years" These are the folks who are supposed to help those who do not know. Anyway thanks again for posting this. Seems there are nothing but idiots in the retail business any more... I do most of my shopping on line now because of that. But for things like tires I will stick to checking out the products in person. Most of the time I don't even bother asking store sales people questions. They very seldom know the answers anyhow.
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Post by bigbill on Sept 30, 2017 10:09:20 GMT -8
Stores don't want to pay much money for help so they don't get much. It's not that sales people are stupid, they just don't give a ****. Most know they could make more money flipping burgers and neither pays a livable wage.
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