Tire Tread Depth Gauges

Next to tire pressure, tread depth is one of the most important factors in evaluating the condition of your RV's tires. Whether you choose a penny or use a stick-type or dial-type tread depth gauge, it is important to never drive an a tire that has a tread-depth of less than 2/32 of an inch. Tread depth is measured vertically by calculating the space between the top of the tread and the bottom of the tire's deepest groove. Tread depth is measured in 32nds of an inch.

In the old days, a U.S. Lincoln penny was used to measure a tire's tread depth. If Lincoln's entire head (including the top) is visible after being inserted into the tread groove, the tire is worn to approximately 2/32" in depth and would be considered legally worn out in most states in the U.S. Nowadays, tread depth is best measured with a tire tread depth gauge.

Modern tires typically have tread wear indicators or "wear bars" located at the base of the widest main grooves, usually equally spaced around the tire. You should remove a tire from service when the wear reaches these tread wear indicators and a tread depth of two thirty-seconds of an inch is all that remains. However, it is helpful to know exactly how much sevicable life is left in your tires so that you can plan for their replacement.

Calculating Useable Tread Depth

A typical tire that has 12/32 of an inch of original tread depth has only 10/32" of useable tread depth. A tire's useable tread depth is calculated by subtracting a worn out tire's remaining 2/32" from a new tire's original depth of 12/32". You would calculate a tire's "tread wear percentage" or "useable tread depth" by subtracting 2/32" from a tire's new tread depth, then compare that number to remaining tread depth. For example, a tire that started with 12/32" of original tread depth and has lost 5/32" due to wear (leaving 7/32" of remaining tread depth) would be 50 percent worn.

Deluxe Tread Depth Gauge at Meyers Tire Supply:

Meyers Tire Supply's stick-type Deluxe Tread Depth Gauge is calibration in 1/32 inches and 0 to 25 mm.

www.myerstiresupply.com

Intercomp's Dial Type Tire Tread Depth Gauge from Amazon.com:

The Intercomp Tire Tread Depth Gauge allows you to check your tire tread depth in seconds. The Intercomp tire tread depth gauge measures tire wear in 1/32" increments. The gauges is made of aluminum construction and comes with a carrying pouch.

Intercomp Tire Tread Depth Gauge 360109

Digital & Dial Type Tire Pressure Gauges

Your RV's "recommended" tire pressure is always to be measured and/or set when the tire is "cold". A tire's "maximum inflation pressure" is the highest "cold" inflation pressure that the tire is designed to contain, however the tire's maximum inflation pressure should only be used when called for in the vehicle's owners manual or on the vehicle's tire placard.

With a large motorhome, the tire inflation pressure needs to correspond to the load at each corner of the RV. To accomplish this, the individual wheel weights must be measured on a scale. You should check with the Recreational Vehicle Safety Education Foundation (RVSEF) for their RV Weighing Safety program and Tire Education program.

RV Safety & Education Foundation (RVSEF) Website:

www.rvsafety.com

www.rvsafety.org

Checking Hot Tire Pressure

The term "cold tire pressure" or "cold inflation pressure" is defined as pressure measured when the ambient temperature is low (usually early in the morning), or before heat is generated from driving. Tire pressure will temporarily increase as the internal temperature of the tire rises. It is normal to experience "hot" tire pressures that are 5 to 8 psi above the tire's recommended "cold" pressure if the tires are exposed to the sun or the vehicle has been driven for any distance.

Continental Load Inflation PDF

Goodyear Load Inflation PDF

Michelin Load Inflation PDF

Checking Hot Tire Pressure

If the tire pressure is several pounds higher than the recommended pressure when checking under "hot" conditions, do not bleed off the excess pressure as this will cause the tire to be underinflated.

Dial Type Tire Gauges at Camping World:

Deluxe Pistol Grip Tire Gauge

Long-Reach Tire Pressure Gauge

Dial Type Tire Gauges at Amazon.com:

Accutire MS-5010 Heavy Duty Dial Tire Gauge

Digital Type Tire Pressure Gauges at Amazon.com:

Accutire MS-4720 Digital Truck Tire Gauge

Learn more about tire pressure at autologic.com.