Tire Maintenance 101

We all know the importance of tire safety but were you aware of just how much they can have an effect on both your CSA ratings and your fuel usage? Unfortunately tires are a place where a driver could shave some time off their daily inspection – most of us have either just kicked or thumped on a tire to see if the pressure is “good enough”. Unfortunately “good enough” could be costing you.

To start, not having your tires at the proper pressure can cause premature wear, a reduced contact patch and increased rolling resistance. Additionally there are 12 possible tire violations possible during an inspection and all of them can result in the vehicle being declared out of service.

The Basics

Where’s a few basics – tire pressure can’t fall below 50% of the sidewall maximum pressure (note OHSA requires tires to be able to maintain a minimum of 80% and any that are running at less than this must be taken off the vehicle and re-inflated in a cage). There can’t be any audible air leaks. No belt material can be showing, not even from a sidewall cut. Tread and or sidewalls must not be separated. Steer tires must have a tread depth of no less than 4/32” and drive tires no less than 2/32”.

If you are looking for a driver gift that will have a great ROI, outfit all of your drivers with air pressure gauges and tire depth tools. Train your drivers on the proper way to use them and get them to document these on their inspection sheets. Make sure that the gauges are made for truck tires, both in terms of pressure and that they are long enough to be used on the inner tires. Why are these a good idea? Studies by Michelin have found that under inflating your tires by as little as 10% (which will not be noticed with that kick or thump) can reduce tire by between 9 and 16% over its lifecycle. On a $400 tire that means additional costs of between $36 and $64. Multiply that by 10 tires for each tractor and there is some serious money to be gained back by investing in approximately $20 of equipment!

Watch those pressures!

A lot of our shops use a generic rule of thumb for tire pressure – most will go with 100 psi. However, this may or may not be the optimal pressure for your tires and/or application. Work with your tire supplier to determine what will be the best pressure. Some tires wear better at 110psi while others operate better at 95 psi. That is where having a trusted tire vendor who knows your fleet and operations is important.

There are a few other things to keep in mind when your drivers are checking tire pressures. First, never check pressures after the tire has been run and is warm. This situation will result in a higher reading than if you check the pressure when the tire is cold. Two – try to maintain pressures for a loaded situation. This will make sure that you set your pressure at a “worst case” scenario and ensure that your tires have the ability to handle the loads you haul.

Mismatches are not good

Some other best practices include matching tread depths and tread patterns. We all have had to throw a mismatch on in an emergency, but doing so on a regular basis can cost you more than you think. Just a difference of 5/16 of an inch in circumference (which will be barely noticeable in tread depth) can result in the smaller tire being dragged up to 13 feet in a mile, or over 200 miles for every 100,000 miles of use. That could be the difference between a drive tire being a good enough casing to recap or not. Just having a slightly different tread pattern could result in that difference.

Some tire maintenance items that you may be missing

Rotate your tires. Bridgestone engineers have found that the first two rotations are the most important as the tires are still setting up their wear patterns. When the tread depths are at their deepest the blocks are more susceptible to wear. This is because once they get shorter they tend to stiffen up and get some resistance. They have also found that there is no magic number when it comes to when to rotate tires. Each individual company will have a different operating area and use pattern that will affect what works best for them. The best idea is to set an initial threshold and then study the wear patterns and extend or reduce the intervals as necessary.

Do a three axle alignment. If your drive axles are misaligned then the truck will want to go straight but the rear end will dog track and wear out the front tires more quickly. Additionally, don’t just use a standard alignment setup. If you tend to do tight turning radii then you may want to set your scrub to a higher level. Again, work with your tire rep to determine what the ideal toe-in/toe-out are for your application, even if they take you one of the extremes of the tolerances.

The last thing is wash the tires on a regular basis. Your tires are constantly picking up chemicals, mud and debris as they roll down the road. Leaving these items on the tires can speed up the deterioration of the rubber which can result in things like tread separation or just increase the air leakage through the sidewalls (a relatively normal amount is about 1 psi per month and 1 psi for every 10 degree drop in temperature). A wash will remove those items and prolong your tire life.