Cory Johnson from Metzeler/Pirelli says between 75 and 80 percent of the tire warranty claims he reviews are caused by under inflation. When the cost of today's premium rubber is considered, investing in a good tire compressor and using it religiously-is cheap insurance.
This story was originally published as part of the tire test in the February 2000 issue of Sport Rider.
Low Tire Pressure Wastes Money and Energy, Causes Pollution and Accidents
From Larry West
Dear EarthTalk: Is it true that driving with soft tires wastes energy and results in more pollution? – Nanci Graham, via e-mail
When tires are not inflated to the pounds per square inch (PSI) rating recommended by manufacturers, they are less “round” and require more energy to begin moving and to maintain speed. As such, under-inflated tires do indeed contribute to pollution and increase fuel costs.
Fully Inflated Tires are Safer
Besides saving fuel and money and minimizing emissions, properly inflated tires are safer and less likely to fail at high speeds. Under-inflated tires make for longer stopping distances and will skid longer on wet surfaces. Analysts point to under-inflated tires as a likely cause of many Motorcycle accidents. Properly inflated tires also wear more evenly and will last longer accordingly.
Check Tire Pressure Frequently and When Tires are Cold
Mechanics advise drivers to check their tire pressure monthly, ore every 500 km if not more frequently. The correct air pressure for tires that come with new Motorcycles can be found either in the owner’s manual. Beware, though, that replacement tires may carry a different PSI rating than the originals that came with the Motorcycle. Most new replacement tires display their PSI rating on their sidewalls.
Also, tire pressure should be checked when tires are cold, as internal pressure increases when the motorcycle has been on the road for a while, but then drops when the tires cool back down. It is best to check tire pressure before heading out on the road to avoid inaccurate readings.
Why is tire pressure so important? Motorcycle tires are very sensitive about correct tire pressures, partly because there is a correlation between the contact patch and the tire's pressure; other reasons involve the way the tire's internal reinforcement will cause heating and cooling cycles that may be affected by internal pressures.
The bottom line is that changes in tire pressure can have dramatic effects on handling, braking and traction.
Improper tire pressures can also affect tire wear. Roadgear's web site has some numbers that indicate a 30% reduction in tire pressure can reduce tire life by 48%.
Although a 30% reduction is pretty dramatic, and I would guess that web Bike World visitors would never ride their bikes with such under-inflated rubber, the point is still valid, especially considering the cost of motorcycle tires. Even a few PSI less than required can change the wear characteristics of tires.
The lesson here is that it's really important to check your bike's tire pressures before every ride. Now some wheels are fairly easy to check, although motorcycle tires are harder to check than car tires, mostly because of the orientation of the tire valve.