Tiffin Motorhomes WAYFARER 2017, Owner'S Manual

Page: 118 / 144

109
ROUTINE MAINTENANCE
Next number—This three-digit number gives the width in millimeters of the tire from sidewall edge to
sidewall edge. In general, the larger the number, the wider the tire.
Next number—This two-digit number, known as the aspect ratio, gives the tire’s ratio of height to
width. Numbers of 70 or lower indicate a short sidewall for improved steering response and better
overall handling on dry pavement.
R—The “R” stands for radial. Radial ply construction of tires has been the industry standard for more
than 20 years.
Next number—This two-digit number is the wheel or rim diameter in inches. If you change your wheel
size, you will have to purchase new tires to match the new wheel number.
Next number—This two- or three-digit number is the tire’s load index. It is a measurement of how much
weight each tire can support. You may find this information in your owner’s manual. If not, contact a
local tire dealer. NOTE: You may not find this information on all tires because it is not required by law.
M+S—The “M+S” or “M/S” indicates that the tire has some mud and snow capability. Most radial tires
have these markings.
Speed Rating—The speed rating denotes the speed at which a tire is designed to be driven for extended
periods of time.
U.S. DOT Tire Identification Number—This begins with the letters “DOT” and indicated that the tire
meets all federal standards. The next two numbers or letters are the plant code where it was
manufactured, and the last four numbers represent the week and year the tire was built. For example,
the numbers 1612 means the 16th week of 2012. The other numbers are marketing codes used at the
manufacturer’s discretion. This information is used to contact customers if a tire defect requires a recall.
Tire Ply Composition and Materials Used—The number of plies indicates the number of layers of
rubber-coated fabric in the tire. In general, the greater the number of plies, the more weight a tire can
support. Tire manufacturers also must indicate the materials in the tire, which include steel, nylon,
polyester, and others.
Maximum Load Rating—This number indicates the maximum load in kilograms and pounds that can be
carried by the tire.
Maximum Permissible Inflation Pressure—This number is the greatest amount of air pressure that
should ever be put in the tire under normal driving conditions.
Vehicle Load Limits
Determining the load limits of a vehicle includes more than understanding the load limits of the tires
alone. On a motorhome, there is a federal certification label that is affixed in the rear closet. The
certification label will indicate the vehicle’s gross vehicle weight rating (GVWR). This is the most weight
the fully loaded vehicle can weigh. It will also provide the gross axle weight rating (GAWR).