Hi All: Since the discussion on tires is getting confused here is the latest Poop on where the rubber hits the pavement. Hope this helps clear up all the questions

Doug

Check this URL for a great description of trailer tires This site also has great discussion of trailer brakes, controls and everything else pertinent to safe towing. A Must Save URL for Airstreamers!: http://championtrailers.com/tire_art.html

Check this out for general tire identification: For tires using the P-metric designation (e.g., P245/50ZR16) Format: [Code][Width]/[Aspect][Speed][Construction][Size]

Code:
P = Passenger
LT = Light truck
T = Temporary
LTP = Light truck, personal use

Width:
Width at widest point, sidewall to sidewall, in millimeters

Aspect Ratio:
Tire height in mm, measured tread to bead, divided by width above, multiplied by one hundred.

Speed ratings:
(The maximum speed the tire can maintain at its maximum load rating)

Q - 100 mph 160kph
R - 106 mph 170kph
S - 112 mph 180kph
T - 118 mph 190kph
U - 124 mph 200kph
H - 130 mph 210kph
V - 149 mph 240kph
W - 168 mph 270kph
Z - more than 168 mph 270kph

Construction:
R - Radial ply
B - Bias belted
D - Diagonal bias

Size:
The diameter of the wheel the tire is designed to be mounted on, in inches.

Other information:
Maximum Air Pressure - This is the max pressure the tire is designed to hold (note this is more than the recommended inflation pressure)

Maximum Load - Weight the tire can support

Load Index - A code that indicates the maximum weight the tire can carry at its speed indicated by its speed rating

Construction - Tells the number and type of plies used in the construction of the tread and sidewall

DOT Serial Number - Identifies the plant, manufacturer, and date of production

Tread Wear Index - A rating of the tire's resistance to wear. 100 is the reference. A 250 rating indicates 2.5 times the wear resistance of the reference tire. This number cannot be accurately translated to mileage.

Traction Index - A rating of the tire's ability to stop on wet pavement. There are three grades, A, B, and C, with A being the best. This index does not reflect the tire's traction performance on dry, snowy, or icy pavement.

Temperature Index - A rating of the tire's ability to dissipate and resist heat. There are three grades, A, B, and C, with A being the best.