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Old 05-16-2018, 06:42 PM   #73
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Join Date: Feb 2010
Location: Taylors, SC
Posts: 1,467
ST Tire Inflation

What seems like a long time ago, Probably about 15 years, I started researching ST tires. At that time there were very few tire manufacturers building the ST tires. The largest and most well known was Carlisle. They saturated the industry with information about their ST tires and were probably the most prolific OEM provider for at least 5 years. (There was also a new and upcoming ST tire builder, Goodyear. They, for a time, overtook Carlisle as leading OEM provider. Then, there was/is CHINA).

When large tire retailing chain stores started stocking Carlisle ST tires, Carlisle provided them with oodles of information about their tires and how they differed from other highway tires.

Carlisle said ST tires could degrade by as much as 10% a year. They had and still have one of the shortest warranty periods of all ST tires. Carlisle recommended their tires be used at 60 MPH or less (TRA sets unmarked ST tires at 65 MPH). Carlisle recommended their tires to be operated at the inflation pressure molded into the tireís sidewall (thatís for MAX load capacity). Carlisle was very stern about their ST tires life expectance saying 3-5 years was the maximum regardless of mileage.

In interviews with information outlets line Modern Tire Dealer, Carlisle spokespersons would spout out their recommendations and ST sellers/users took notes. Almost everything you read about ST tires in Discount Tireís on-line publications are excerpts from Carlisle PDFs. So, their recommendations became the norm.

ST tires on todayís market have come a long way from where they started. But, donít get me wrong. Iím not against max pressure for ST tires. Itís almost always recommended by the vehicle manufacturerís and when thatís the case the max is also the min. But, thatís not so for replacement tires with excess load capacity. The canned answer from the replacement tire rep will be to use what is recommended by the vehicle manufacturer. So use as much extra load capacity as you are comfortable with. Most of the time itís not going to be the 110 PSI the tire needs for max load. 90 or 100 PSI may provide the extra load capacity you need for excess load protection and a better ride.

Just about every ST tire now purchased has a speed rating of 75 MPH or higher. Every MPH you travel under the tires speed rating provides a little more protection from overheating a tire when itís close to its maximum load. Before the higher speed ratings all we had was 100% inflation protection at 65 MPH.

Back to the Carlisle thing. If you did not archive any of their old PDF forms youíre out of luck. Their new ST tires are up-to-date and in line with all other ST manufacturerís and with speed letters in the 81 MPH range. At a recent BASS fishing show the only tires close to outnumbering the Carlisleís were Passenger tires. A lot of the large dual axle rigs really liked the low profile passenger tires. (RV trailers and boat trailers are built to the same FMVSS standards, the vehicle manufacturer decides what fitment is appropriate).
An Old Navy Aircraft Mechanic that writes about tires.
Our rig. NC mountain pull-off. US-19.
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