Can't find speed rating

[Cup_fan]

I have Ridgway Sport tires on my 2015 Rockwood 8315BSS travel trailer. I can't find a speed rating for these tires anywhere on the sidewall. They are ST225/75/R15 load range c. The only other thing I can find is H178 after the size, but I don't know what that means. I'm assuming they are rated at 65 mph, but would like to know for sure. I can't find anything about these tires anywhere online. Does anyone have these tires or know anything about them? Do some tires not have the speed rating on the sidewall? They are load range C, and the air pressure is 50 psi. And they are made in China.
We are planning a trip to Montana this summer and I want to make sure I have all of my ducks in a row, so I was trying to find some reviews on these tires.
Also, I read an article by Bob Livingston a few years back about the pressure. He said that the pressure on the sidewall is the "minimum amount of pressure required to carry the maximum load", and that you should run 5 or 10 lbs above what's stated on the sidewall. Has anyone else heard this, and what do you do? I typically run at or just slightly above the sidewall number. But most of my trips are within 100 miles of home, but this will be the first trip of this magnitude, so i'm trying to re-educate myself.

[Cup_fan]

geneeich wrote:
I know this is late, but just pickup a new 2016 Rockwood Ultra Light 2906WS and it has Ridgeway Sport ST tires the same as yours. Mine are clearly marked Load Range C, Speed Rating L 75mph max speed, but little hard to read.

Hope this helps.

Any chance you might have a photo? Mine are clearly marked load range c also, but I can't find any resemblance of a speed rating.

[goducks10]

My GY Marathons on my 5th wheel and my Carlisle Dura Trail tires on my utility trailer have no speed rating marked on the sidewalls.
Guess I'm good for 75-80mph. 🙂

[geneeich]

I know this is late, but just pickup a new 2016 Rockwood Ultra Light 2906WS and it has Ridgeway Sport ST tires the same as yours. Mine are clearly marked Load Range C, Speed Rating L 75mph max speed, but little hard to read.

Hope this helps.

[Cup_fan]

CALandLIN wrote:
Here is a picture of how the speed rating is displayed on this particular ST tire. Even though the tire service description is not the official weight description for LT & ST tires they are still allowed to be on the sidewalls for reference purposes. The letter "L" behind the 113/108L is for a 75 MPH tire.

ST Speed Letter PIX

No such number/letter combo on my tires. I've not been able to find anything on these tires that resembles the speed ratings that I've seen on other tires during my research. I can find all other information except that. It's just ST225/75/R15 followed by H178 and that's it. So I think I just have to assume that they are rated for 65 mph.

[CALandLIN]

Here is a picture of how the speed rating is displayed on this particular ST tire. Even though the tire service description is not the official weight description for LT & ST tires they are still allowed to be on the sidewalls for reference purposes. The letter "L" behind the 113/108L is for a 75 MPH tire.

ST Speed Letter PIX

[ktmrfs]

TucsonJim wrote:
Unless your ST tires are specifically marked with a speed rating, they are manufactured to be run no higher than 65mph. There are very few ST tires rated for speeds higher than this.

sorta true. ST is 65mph, BUT currently Maxxis, Carsilie, Towmax, and Goodyear have ST tires rated for above 65mph and not all have additional speed rating stamps. Maxxis is up to 85mph but load and inflation need to be adjusted per an email I have from them. Towmax says L on the data sheet. Carslie, doesn't appear to have a sidewall stamp but I have an email from Carsilie with the tire spec sheet showing "M" for the speed rating w/o reducing the load capacity. Goodyear has specs for running at 75mph, reduces load rating slightly since you up the tire pressure by 10lbs above the pressure for a given load but NOT to exceed sidewall max pressure.

[Cup_fan]

Scrubjaysnest, I checked, July 2014. So they are about a year older than my camper.

[scrubjaysnest]

You also need to check the date code the tires were made! Ours had been sitting around in a warehouse somewhere for two years before they were put on the new camper.

[Cup_fan]

BB_TX, thanks for your links, I read those articles during my search for the speed rating for my tires. I'm coming to the conclusion that there is no speed rating code on my tires, in which case I would agree with TucsonJim that I should assume that it's 65 mph. I'm still curious as to what the H178 means. It almost sounds like a tire size that you would have found on the old bias tires from years ago. But from my research, I don't think it has anything to do with the speed rating.

[Cup_fan]

Old-Biscuit, thanks for the link. I went to the website and still couldn't find my tires. I have the Ridgway Sport Power Touring tires, and there wasn't any information about them. I might just have to give them a call.

[Old-Biscuit]

LionsHead Specialty Tire

[Turtle_n_Peeps]

Cup fan I can't tell you about your tires.

What I can tell you is what "I" do. I've ran every type and brand of ST tires made and known to mankind. I always fill them to max pressure on the sidewall and many times 10 over. I always run fast. Most of the time 70+ and always in hot weather since I take all my vacation time in July. A few times 80 in hot weather for hours at a time.

My score card? Blew one tire in 35+ years of towing. And that was almost for sure a nail or screw that I didn't catch in time.

Do I suggest to do what I do? Nope. Just stating my experience to show that if you go over 65 and have my luck you will be fine. 🙂

[TucsonJim]

Unless your ST tires are specifically marked with a speed rating, they are manufactured to be run no higher than 65mph. There are very few ST tires rated for speeds higher than this.

[BB_TX]

How to read speed rating.

Speed rating for ST tires.