CapriRacer wrote:
FastEagle wrote:
Ok, here is one for the engineers. Just how much credence do you put on a tires speed restrictions? The individual tire manufacturers are the ones that self impose speed limits for their RV trailer tires or others used on other recreation vehicles.......
If you look in the Tire and Rim Association (TRA) Yearbook, you'll find the speed restriction listed - so I don't think you can say it is the manufacturers that self imposes the restriction - at least, not in the normal sense.
FastEagle wrote:
.......
I hate to bring brand names into a discussion but it’s necessary here to show where such information might be found.
Click here, on the Carlisle tire page click on the resources tab and then open the PDF; Trailer tire maintenance. In the PDF file you will find that Carlisle is very careful about how they word the speed limit of 60 MPH for towing trailers. When filing claims against Carlisle trailer tires I would also be very careful not to admit constantly operating my trailer over 60 MPH........
I find it interesting that they word their statement the way they do. Part of the problem here is that Tire and Rim has different speed restriction for different sizing groups.
For example: On tires with the sizing form like "4.80-8", TRA shows a speed restriction of 100kph (62 mph), where for tires with the sizing form of "ST205/75R15", TRA uses 65 mph (no metric units listed).
So intrepreting the Carlisle document. it appears they are being conservative rather than accurate.
FastEagle wrote:
........Here I’m going to talk about a specific tire. It’s talked about a lot on the internet tire threads but is yet to be tested as an Original Equipment tire. I bring this particular tire up because it has a double standard speed rating. It’s the Michelin XPS Rib. If a buyer goes down to their local Michelin retailer and purchases some XPS Ribs as replacements for some ST tires they will most likely get XPS Rib tires with a “Q” (99 MPH) speed symbol molded into the tire. When that same tire is used as OE on a RV the symbol is omitted and the specs in the RV usage section of the Michelin document will list the speed rating for that use as 75 MPH. Because the tire is not used as OE in the RV trailer industry it’s a toss-up as to it’s speed restriction on those axles. Can you shed some light on that?
url's omitted
FastEagle
I interpret that differently. I think what Michelin is trying to say is that if these LT tires are used in LT service, the tire has a Q speed rating - and when used in an RV service, they recommend restricting the speed to 75 mph. It has nothing to do with OE vs replacement - and I'll bet that if you find an RV that comes with those tires they have a Qspeed rating on the sidewall. In other words, those statements aren't contradictory.
As long as FE brought up the XPS RIB, would you mind writing a little on the commercial grade tires like the RIB, Bridgestone Duravis R250 and Goodyear G949 RSA? Seems that those of us that use them feel they are the best choice available. Chris
