s the Metzeler Dealer Support Truck rolls across the country to various outdoor events, the number one consistent message delivered to consumers is how important tire pressure and using the proper tire is for their motorcycle. The event team is particularly adamant when reminding consumers that installing a tire with the required load rating and the tire manufacturer’s recommended pressure results in the best possible mileage and performance.
     While your local dealer may have a different recommendation, Metzeler urges riders to use the tire manufacturers fitment guides, as they thoroughly test, approve and recommend fitment for every vehicle, including the fitments for Harley-Davidson motorcycles. Metzeler offers replacement fitments for every make and model, as well as Stage 1 and Stage 2 larger width and larger diameter upgrades to suit the preferences of the rider. For example, on touring bikes like FLHT Electra Glide and the newer FLTR Road Glide, Metzeler recommends the Alpha size upgrade ME880 tires.
     New for 2008, Metzeler now offers the ME880 160/70B17 “D spec” tire with an (H) speed and (73) load-rating for use on the various Deuce and newer Dyna models. Designed for the V-Twin market this new tire has a very attractive price and is significantly less than the BMW K1200LT specific 160/70B17 ( HYPERLINK "javascript:partInfo('11010448')" \o "Display Part Detail for 11010448" 110-10448).
     According a Statistics Center of the NHTSA (National Highway Transportation Safety Administration), over one-third of vehicles have at least one tire that is 20 percent below the necessary pressure for the particular vehicle and its load capacity. Approximately one-quarter of vehicles have at least one tire that is 25 percent below the necessary pressure. For a tire whose minimum cold psi is 44 lbs., this represents a discrepancy of 11 psi from necessary pressure; this would be considered significantly under-inflated by any tire manufacturer. One supplier of tire pressure monitoring systems, SmarTire Systems, Inc. of Richmond, British Columbia, has found that nearly 50 percent of all motorcycle tires are under-inflated to some degree.
Under-inflation also has a potentially large impact on safety, tire life, and fuel economy. It affects handling and braking (stopping distance), 20 percent under-inflation reduces tire life by a third and added rolling resistance means lower gas mileage.

     1. Reduced Vehicle Safety–Tire Failures and Increases in Stopping Distance
When a tire is used while significantly under-inflated, its sidewalls flex more and the air temperature inside the tire increases, increasing stress and the risk of failure (possibly resulting in flat tire.) In addition, a significantly under-inflated tire loses lateral traction causing a tendency for the motorcycle to “wander,” making handling more difficult. Finally, significantly under-inflated tires can increase a vehicle’s stopping distance, especially in the wet.

2. Reduced Tread Life
Data submitted to the NHTSA indicate that, when a tire is under-inflated, more pressure is placed on the shoulders of the tire causing the tread to wear incorrectly. The data also indicates that the tread on an under-inflated tire wears more rapidly than it would if the tire were inflated to the proper pressure.

3. Reduced Fuel Economy
Under-inflation increases the rolling resistance of a vehicle’s tires and, correspondingly, decreases the vehicle’s fuel economy. According to a 1978 report, fuel efficiency is reduced by one percent for every 3.3 psi of under-inflation. Thus, for a tire that is 25 percent under-inflated (11 psi), its fuel efficiency will be reduced by 3.3 percent.
     The importance of observing proper tire inflation pressures cannot be overstated. Adhering to manufacturer-approved guidelines will not only result in a more enjoyable ride, but also in more even wear, increased mileage and enhanced performance. By taking this simple step to protect your tires, you’ll ensure that your bike will continue to give you its best for years to come.