Trailer tires and speed ratings

[Orlando3]

Need to clarify something. Are ALL trailer tires i.e., ST tires limited to 65mph regardless of a speed rating clearly posted on the tire?


Sent from my SAMSUNG-SM-T817A using Tapatalk

[mfifield01]

Originally Posted by Orlando3

Need to clarify something. Are ALL trailer tires i.e., ST tires limited to 65mph regardless of a speed rating clearly posted on the tire?


Sent from my SAMSUNG-SM-T817A using Tapatalk

From my understanding, the speed rating on tire is correct. In the past, ST meant that it would only go to 65. Now they have been rating them above 65. Mine are rated to 75, but I rarely go over 65.

[Tbos]

Some of the newer tires have higher speed ratings. I agree it's better to keep it below 65 for control, stability and safety.


Sent from my iPad using Tapatalk

[CWSWine]

ST tires without speed ratings are limited to 65 MPH but if they have a speed rating that rating is good. Mine have "R" 106 MPH but if you see mine going faster than 70 call the cops because it has been stolen.

[Orlando3]

Ha ha......will do. Thanks for the info. That's what I thought also but wanted to make sure.

Sent from my SAMSUNG-SM-T817A using Tapatalk

[CWtheMan]

There are a few catch 22 problems with speed ratings for ST tires.

1. There is no speed letter for 65 MPH. For many years it’s been well published that ST tires without a speed rating on their sidewalls are limited to 65 MPH.

2. The USA has told many of the China manufacturing plants to include speed letters on their ST tires or pay higher tariff fees.

3. ( A service description identifies the tire's load index and speed rating). Herein lies the biggest of the catch 22s. Service descriptions are not official for ST & LT tires. They were allowed to be displayed on the ST & LT tires in the hope they would become a single description for all tires. It has not happened and the Load Range (Ply Rating) still remains official for the ST & LT tires.

The China plants in all their wisdom have included the speed letter at the end of a service description for their ST tires. Is it valid? I don’t know. From a knowledgeable source I’ve been told that the TRA is still holding firm on the design features of the ST tires being limited to 65 MPH.

I don’t know if I would trust the China speed letters without NHTSA getting involved and confirming the letters to be valid.

Reference:

http://kenjonestiresblog.com/blog/st...ailing-duties/

[gearhead]

CW I would think (hope?) that anything molded into the sidewall of a tire sold in the US would be reviewed and approved by NHTSA.

[CWtheMan]

Originally Posted by gearhead

CW I would think (hope?) that anything molded into the sidewall of a tire sold in the US would be reviewed and approved by NHTSA.

IMO the China manufacturer would be required to inform NHTSA they have changed their tire molds to include the speed letters. There is a 3rd party involved, USA Customs. They would verify the tires meet the tariff requirements. All passenger tires have speed letters at the end of their service descriptions. The customs officials may not know the service description is not official for ST tires. The DOT (NHTSA) does not do physical inspections. It's initially done by the manufacturing factory. NHTSA will only get involved if an unsafe condition is suspected.

I'm working on a letter requesting an interpretation. It always takes a month or two and with a new administration taking office I suspect it will take longer.

Here is another reference to ponder. Roger is known as Tireman9 on RV forums.

http://www.rvtiresafety.com/2015/03/...ler-tires.html

[EVMIII]

From a purely unscientific perspective, it is my experience dragging things of various weights and sizes over the last 30 years that every vehicle/trailer combo have a sweet spot. That speed that maximizes speed, fuel economy, RPMs, etc. My current rig seems to like 67 mph. I can drag it considearably faster if I have too, but fuel economy seems to drop proportionally. I expect this might adjust when I swap tires this summer and I will adjust accordingly. Find your happy spot and cruise. Safe travels.