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Cup_fan's avatar
Cup_fan
Explorer
Mar 22, 2016

Can't find speed rating

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.
  • 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.
  • 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.
  • 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 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.

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