Tires

A tire looses 1 psi for every 10 deg F drop in temperature. Tire pressure should be checked a minimum of every 30 days.

John -

This is too complex of a question to offer a simple number. Each P&D fleet will have a different average mileage life. The mileage is dependant on a number of issues, route factors like long runs or short runs, road conditions, and climate. Other factors such as maintenance practices and driver skill also impact mileage. The mileage distribution from fleet to fleet can vary from 5k miles to 100k miles using the same tires. So offering you an "average" number is not possible.

The G647 currently comes in two different compound options the G647 RSA which is being phased out and the G647 RSS. The RSS has a new tread compound for improved tread life which will also impact mileage.

Your best bet for selecting tires for your application is to compare different tires using similar trucks, driven on the same routes, with equally skilled drivers and you will find that the G647 performance is worthy of the Goodyear name.

Each manufacturer has their own proprietary method for calculating the footprint shape which drives even tread wear. This may explain why you have not had any luck in your quest. However, many manufacturers, Goodyear included, publish the gross contact area for their tires in their engineering data books. See www.goodyear.com/truck for a copy of Goodyear's book.

Briefly consulting the Goodyear book for the G314 11R22.5 trail tire the gross contact are is listed as 62 in^2. The gross contact area does not subtract out for any grooves.

Good Luck!

Joe-

The front axle on a spread axle trailer experiences a tremendous amount of scrub when cornering the trailer as it often acts as a pivot point for the trailer. There are three factors that impact the scrub effect on a tire in this position: tread depth, shoulder design, and the amount of spread.

Having a shallow tread depth minimizes the amount of lateral force and stress transferred to the shoulder and will prolong the tire life.

Selecting an open shoulder design or a shoulder design with stress relieving sipes will also minimize the amount of shoulder that is "grabbed" by the road and folded under during sharp radius turns.

Reducing the spread between axles will minimize the scrubbing effect. A 60" spread will be more damaging to your tires than a 48" spread.

The new tires best suited for this design are the Dunlop SP181A and the Goodyear G314 trail tires both available in the size you are looking for.

Goodyear has specifically designed a retread for the spread axle position called the G319SA (SA=Spread Axle)if you already have good casings You may want to consider this option.

The spread axle trail position is extremely demanding on a tire and no tire is perfectly designed to withstand this amount of scrub, but selecting the right tread depth and shoulder design will help you go farther.

RPMs can be found in the technical literature for any tire manufacturers. See www.goodyear.com/truck for a complete listing.

In goodyears literature I see

11R22.5 = 504 RPM
11R24.5 = 481 RPM

295/75R22.5 = 517
295/75R24.5 = 503