What tyre pressure are you running in your steer, drive, and trailer tyres? If it is 100 psi, like most do, your steer tyres are 20 per cent under inflated, which increases tyre temperature, and reduces steering accuracy. The drive tyres are 33 to 300 per cent over inflated, and the trailer tyres are 85 to 400 per cent over inflated.
Optimum tyre pressures at maximum legal loads for 11R or 295 tyres is 120 psi for steer, 75 psi for tandem drive tyres, and 55 psi for tri axle trailers.
All tyre manufactures, and the NHVR’s PBS Tyre Review recommend these pressures. AIR CTI has been recommending and using these pressures for nearly 25 years.
When the load is removed, tyre pressures should be reduced. On lightly loaded tyres, optimal highway tyre pressures are often only 30 psi.
My customers, and my own trucks do this all the time. For instance, many empty tandem drive tray trucks will have only 4 or 5-tonne on eight tyres. That means each tyre supports about the same weight as a Toyota Prada. No one would run 100 psi in their SUV.
The correct footprint for an 11R22.5 tyre is 427 square cm or 66 square inches. That is 24cm long, 18.5cm wide. This ideal size exists only if the pressure is matched to the load.
For instance, the footprint, the amount of rubber on the ground on an empty tri axle semi is only about the size of a credit card, and we expect the trailer to trail?
Go out and have a look at your tyres. The steer tyres will have a substantial flat area where it meets the road, that is probably 250mm long. It is under inflated.
Your drive tyres, if loaded, will have a flat area that may be 100mm long, if you are heavily loaded. Otherwise, the tyre will be round at the bottom. This means the outer part of your tread is doing no work at all. In fact, the outer part is being ground away, causing scalloping or outer rib wear. And the trailer tyres are even worse.
Safety is reduced. Braking distance increases. Trailer and truck swing increases. High vibration levels damage the driver’s health and wears the driver out with excess stress.
Steering and handling is worse, increasing driver stress even more. Lack of warning of air loss means deadly blow outs often end in the scrub, if you’re lucky.
The waste in tyres is at least 30 per cent, but probably 50 per cent!
You are wasting thousands of dollars every year just in tyre waste, shortened tyre life, increased punctures, blow outs, and uneven wear.
Over inflated tyres act like super balls, amplifying every road bump or irregularity, hammering the suspension, the wheel bearings, axles, and your truck into an early grave. Optimal pressures double diff life, transmission life, triples suspension life, and even doubles suspension seat life. How much does that cost you?
Uneven tyre pressures in duals causes one tyre to ride a little higher, carrying a bit more weight. This causes the other tyre to wear uneven, and both tyres to wear quicker. Uneven tyre pressures increase rolling resistance, using more fuel.
A complete tyre pressure management system makes pressure management easy, while added safety, reducing costs, and reducing down time. Your truck is safer and lasts longer.
As an example, if trucks are replaced every five years, the cost of the truck (say $200,000 replacement cost) will be around $40,000 per year. If it lasts seven years, the cost reduces to under $30,000. That is a saving of $70,000. Proper Tyre Pressure Management adds at least 40 per cent longer reliable truck service life.
Add in the reduced fuel use, reduced tyre use, reduced down-time, reduced breakdowns, and increased profit-time, and a Total Tyre Pressure Management System pays for itself every year, year after year.
AIR CTI is the absolute best Tyre Pressure Management System. It’s made in Australia, tough and reliable. AIR CTI fits every truck and trailer, and is the best investment you can make toward your future.
See AIR CTI at the Brisbane Truck Show in the foyer, site 027. AIR CTI should be on your truck.