Was doing some tire research this morning and came across this document at Goodyears web site. http://www.goodyear.com/rv/pdf/marathon_gen_info_032806.pdf

It basicly states an ST tire is good for speeds to 75 if OVER INFLATED BY 10 PSI.

Interesting information

Need to read the whole document to get the full facts. IMO this is a poor strategy if tire blowouts are not wanted....

http://www.goodyear.com/rv/pdf/marathon_gen_info_032806.pdf

Key points
Based on industry standards, if tires with the ST designation are used at speeds between 66 and 75 mph, it is
necessary to increase the cold inflation pressures by 10 psi above the recommended pressure for the load.
o Do not exceed the maximum pressure for the wheel.
o If the maximum pressure for the wheel prohibits the increase of air pressure, then the
maximum speed must be restricted to 65 mph.
o The cold inflation pressure must not exceed 10 psi beyond the inflation specified for the
maximum load of the tire.

I could see doing this with a small trailer if you were not heavy- But doing this with a toy hauler just sounds like a recipe for problems! Most ST tires on fifth wheel toy haulers are already at or above their load design so better to just man up and get good tires!

I don't tow a toy hauler, I tow a boat. With 3 axles I am within weight limits of the tires but looking for a little piece of mind at the speed limit of the tires. I would love to go to a better tire but find me one. 16" wheels are NOT an option as clearance and boat height are both issues. So that leaves me stuck with 15s and ST tires unless you have some suggestions.

I don't tow a toy hauler, I tow a boat. With 3 axles I am within weight limits of the tires but looking for a little piece of mind at the speed limit of the tires. I would love to go to a better tire but find me one. 16" wheels are NOT an option as clearance and boat height are both issues. So that leaves me stuck with 15s and ST tires unless you have some suggestions.

A couple years ago I wanted to change my trailer tires to LT also and keep the same (or better) weight capacity. I was told I could not get a 15" LT tire that would equal the weight rating of my ST 15' tires. So I actually had to enlarge up to 16" LT to achieve the same weight rating as my factory ST 15" tires. Of course I also had to buy new wheels and I did not have clearance issues.

A couple years ago I wanted to change my trailer tires to LT also and keep the same (or better) weight capacity. I was told I could not get a 15" LT tire that would equal the weight rating of my ST 15' tires. So I actually had to enlarge up to 16" LT to achieve the same weight rating as my factory ST 15" tires. Of course I also had to buy new wheels and I did not have clearance issues.

On many rigs you can adapt to 16 inch wheels but it was not a viable option with our Springdale! Clearance was an issue. We had to stay with 15's but opted for an increased load range tire (10 ply E rated Denman) and new aluminum wheels capable of holding the 80 PSI. 65 mph is as fast as I want to tow anyway! Not as good as a 16 inch mod but the best we could do!

On a side note...I just received a TST TPMS and went to have "metal valve stems" installed per factory instructions and my tire dealer said you can't put metal stems in my aluminum wheels! Something about the hole is to small for the nut and washer on the outside of the wheel. Anyone aware of a metal stem that might work?

St tires ran at 10 or even 15 pounds over will not hurt anything at any speed. they will roll better and flex less creating less heat and heat is what makes blow outs happen most of the time. I ran 8ply st225/75/15 at 80psi for over a thousand miles with around 14k of load divided onto four of them max between all four was rated at around 10k at 65psi.

I also had our TT tires changed from Carlisle D rated to Denman E rated 15" tires. the guys at Discount Tire looked at the TT factory wheels and assured me that these would handle the higher psi with no problem. I almost went with aluminum wheels but didn't want to spend the extra money at that time. I've been pulling the TT for almost 2 years now with no tire issues. I think 65mph pulling a trailer is fast enough. I also installed the TST tire monitor, huge peace of mind.

65 mph for me in transport is not enough for me

too much delivery to do in a same day :(

ill have to live with the tire explosion I guess

i have 4 marathon D rating

they have 1 month and they are very good even at 70-75 mph at 60 psi

An easy solution is to upgrade to Cooper Custom Trailer Plus 225/75/15st. I tow 50k+ miles per year and after 10 years of trailer blowouts etc -I have not had a single issue at 80+mph and lots of miles. These tires are AMAZING..

I liked them so much that I went to Cooper Zeon's for the truck ( to replace my 40k Terra Grapplers ) And they are wearing like steel & ride great.

An easy solution is to upgrade to Cooper Custom Trailer Plus 225/75/15st.

My understanding is they have been discontinued.

I heard that rumor last year, but they are still in good supply down here in FL.

Was doing some tire research this morning and came across this document at Goodyears web site. http://www.goodyear.com/rv/pdf/marathon_gen_info_032806.pdf

It basicly states an ST tire is good for speeds to 75 if OVER INFLATED BY 10 PSI.

Interesting information

Actually, it says "if" you are going to go that fast...it does not say you can or should. Here's the quote:

"Based on industry standards, if tires with the ST designation are used at speeds between 66 and 75 mph, it is
necessary to increase the cold inflation pressures by 10 psi above the recommended pressure for the load."

I would just ditch the "ST" tires and go with an "LT" tire. Then you can go as fast as you like and scare the crap out the rest of us. LOL! I am pretty sure I will be switching over when that time comes also. I am going with the "F" rated good years in 235/85/16. I think it is hard to come by a decent trailer tire anymore.

I would just ditch the "ST" tires and go with an "LT" tire. Then you can go as fast as you like and scare the crap out the rest of us. LOL! I am pretty sure I will be switching over when that time comes also. I am going with the "F" rated good years in 235/85/16. I think it is hard to come by a decent trailer tire anymore.

Those of you with 16" wheels are lucky and this is an easy swap. There isn't much out there in a 15" with the right load range.

Those of you with 16" wheels are lucky and this is an easy swap. There isn't much out there in a 15" with the right load range.
...and you guys with 15's are luckier than me with 14's! :)
Having a helluva time finding a decent tire in 185/75/R14 for my 6x10 3500lb single axle trailer. i think I'm going to have to step up a bit....

Thought I would bring this thread back up for those looking for a decent tire in a 14" or 15" size for their trailers. After a lot of searching it appears that a couple of companies are making highway rib style LT tires in these smaller sizes for the increasingly popular small delivery and work vans. Here are the choices I have found

Continental Vanco 2 (http://www.tirerack.com/tires/tires.jsp?tireMake=Continental&tireModel=Vanco+2)
Yokohama Y356 (http://www.tirerack.com/tires/tires.jsp?tireMake=Yokohama&tireModel=Y356)

In the 14" sizes the 185R/14 comes pretty close in diameter of a 20575R14 trailer tire at 25.7 for the 185R/14 vs 26.1 for the trailer tire. Plus the have a load rating of 114# per tire greater and of course don't care the ST speed rating of 65.

I will be most likely installing the Vanco 2 tires sometime this summer. No long tow until next winter but will keep everybody posted.

I would just ditch the "ST" tires and go with an "LT" tire. Then you can go as fast as you like and scare the crap out the rest of us. LOL! I am pretty sure I will be switching over when that time comes also. I am going with the "F" rated good years in 235/85/16. I think it is hard to come by a decent trailer tire anymore.


I was under the impression that what made a tire an ST tire was the construction of the side wall.....have you ever watched the abuse a trailer tire on a dual or tripple axle takes when being back or turned at a harsh angle? I do not believe LT tires are designed to take the type of abuse...hence the trailer service desginator on an ST tire....but like I said that is just a personal belief.....what I have read and take as law is this (http://www.discounttire.com/dtcs/infoTrailerTireFacts.dos)
Personally I will only tow faster than 65 when I am passing someone doing considerably less than 65....and then I back it down to 65....IMHO there is no reason to go any faster when towing....its just good sense

The sidewall flex IMO during maneuvering is minimal abuse in comparison to the work they do while towing. I tow a double axle trailer that is right at its limits for the axles and tires. While I am not condoning or suggesting towing at speeds above 65, that is a personal decision only the driver can make. But what I do know is that I have lost several tires over the years, all do to tread separation. Tread separation can directly be attributed to load and speed. And towing at 65 with 1750# on a tire that is rated for 65 and 1750# leaves NO margin for safety. While there are many V speed rated tires out there on cars I don’t think many would suggest you need to drive 149 MPH either. I personally would feel much safer running a 100mph tire at 65 then a 65mph tire at 65.

...and you guys with 15's are luckier than me with 14's! :)
Having a helluva time finding a decent tire in 185/75/R14 for my 6x10 3500lb single axle trailer. i think I'm going to have to step up a bit....


Maxxis sells an E-Rated (80 PSI) trailer tire in 15". I have their D-Rated on my trailer and it has about 12K miles. Tires don't ever loose any air and they are wearing fine. Next year they will be 5 years old and I'm wondering if I change them.

I was under the impression that what made a tire an ST tire was the construction of the side wall.....have you ever watched the abuse a trailer tire on a dual or tripple axle takes when being back or turned at a harsh angle? I do not believe LT tires are designed to take the type of abuse...hence the trailer service desginator on an ST tire....but like I said that is just a personal belief.....what I have read and take as law is this (http://www.discounttire.com/dtcs/infoTrailerTireFacts.dos)
Personally I will only tow faster than 65 when I am passing someone doing considerably less than 65....and then I back it down to 65....IMHO there is no reason to go any faster when towing....its just good sense

Many, many 5'ers have LT tires standard as they come out of the factory. Yes I have heard of the side wall claims yet why do they use LT. Those trailers are usually in the 10 to 11K empty rating though and have 16" wheels. Once you get to 16" wheels that bring the nice Michelins into play.

I have no idea where anybody tows at 70 MPH. I know a friend of mine does it but I don't feel safe at all because there is always some knucklehead around me and I fear the front of my 5'er coming thru the back of my truck into my kids in an accident. No way I'm towing over 65 and I am mostly under that.

I was under the impression that what made a tire an ST tire was the construction of the side wall.....have you ever watched the abuse a trailer tire on a dual or tripple axle takes when being back or turned at a harsh angle? I do not believe LT tires are designed to take the type of abuse...hence the trailer service desginator on an ST tire....but like I said that is just a personal belief.....what I have read and take as law is this (http://www.discounttire.com/dtcs/infoTrailerTireFacts.dos)
Personally I will only tow faster than 65 when I am passing someone doing considerably less than 65....and then I back it down to 65....IMHO there is no reason to go any faster when towing....its just good sense

ST = Special trailer
LT = Light truck

The sidewalls are constructed different on the ST's where comfort is not as important.