TMC’s RP 235A recommends using a high-quality tire gauge, calibrated regularly from a master gauge for accuracy.
By Jim Park, Equipment Editor
Weekly tire pressure checks might seem unrealistically ambitious, but given what’s at stake in terms of tread wear and tire life, it’s a worthwhile goal. Regular tire inspections should, obviously, include pressure checks. The more frequently you do them, the better the chances of saving a slow leaker.
Tire life decreases exponentially with underinflation. According to TMC’s RP 235A – Tire Inflation Pressure Maintenance, running a tire 20% underinflated shortens its life by about 12%. Running a tire 30% underinflated lops about 30% off its expected service life. It only gets worse as pressure drops.
TMC’s RP 235A recommends using a high-quality tire gauge, calibrated regularly from a master gauge to ensure accuracy. As for the actual operating inflation pressure, users should consult the Load and Inflation tables relating to particular tire sizes and anticipated loads. Interestingly, a typical 22.5-inch low-profile tire run in dual configuration is considered properly inflated for the load carried on a 34,000-pound tandem grouping at only 75 psi. That same tire in a steer position requires 110 psi for the 12,000-pound load on a steer axle.
Overinflating tires in dual positions to 95 or 100 psi is acceptable, and it provides a margin of error for underinflation if pressure checks are not conducted regularly.
The biggest risk in dual tires is inconsistency. RP 235A notes that a pressure differential of just five psi across the tires in a dual set creates a difference in circumference between the tires of up to 5/16 of an inch, and that difference in circumference increases with a wider pressure differential. Two tires of different circumference will not cover the same distance over a given number of rotations, but because the wheels are bolted together, the tires will scrub along the road, causing rapid and irregular wear.
From the March 2012 issue of HDT
Printer Friendly Version
Email This Story
Tires: Related News
3/22/2012 – Regular Tire Pressure Checks are Worthwhile
Weekly tire pressure checks might seem unrealistically ambitious, but given what’s at stake in terms of tread wear and tire life, it’s a worthwhile goal. Regular tire inspections should, obviously, include pressure checks….
More
3/21/2012 – Protecting Your Investment With Proper Tire Inspections
There’s more to a proper tire inspection than kicking it with a cold boot….
More