For us idiots like me, here we go

How To Read A Tire Size
The sidewall of a tire makes good reading - if you know how to interpret the information you'll find there. Take a look at these basic definitions.


1. 205 Width of the tire in millimeters.
2. 55 Aspect ratio - This sidewall's height is roughly 55% of the tire's width.
3. R For radial construction
4. 16 Nominal rim diameter code of the wheel on which the tire fits.
5. 88 Load index is a numerical code associated with the maximum load a tire can carry under certain service conditions.
6. V Speed symbol - This tire can carry a specified load under specified service conditions at speeds up to 149 mph.
7. 88V Service description, a combination of the Load Index and Speed Symbol.

Service Description
The service description contains a two-digit number (load index) and a letter (speed rating).
In this example (left) the service description has a load index of 82 and a speed rating of H.

Note: Some size designations may be preceded by a "P", signifying Passenger or "LT", signifying Light Truck.

__________________
" I GOT CHU GOOD ! "

Do you know what the difference is in the "wear" numbers ....lets say the tire that is on the car now has a wear number of 420 and the new tire that you're considering to buy has a wear number of 320 ..... what does it mean? ....also, how many different speed ratings are there and what is the maximum speed of each of those ratings? .....what do you know about the "tempature" rating that is usually designated by a letter, such as "A", "B", or "C" ??

__________________
'04 SexySilver KC XE ....120k miles....the usual mods.

Holy crap. Give me a few days and Ill answer that

Two of your questions are about the Uniform Tire Quality Grade Standards (UTQG) of Treadwear Grade, and Temperature (Resistance) Grades

The other question, on speed rating, is a European thing, because some of their roads don't have speed limits and they try to establish top speeds of tires based upon the vehicles they are used on.

UTQG Treadwear Grades
The 320 tread wear tire should last less than a 420 wear tire. The numbers are based on a government standard tire that is assigned a 100 tread wear. Manufactures run their tire on a 7,200 mile total course and compare to the standard. So a 300 is supposed to last 3x the standard, a 400 ... 4x. But the initial wear doesn't necessarily coorelate to the entire life. Usually the very high numbered tires are less "sticky" and aren't as good on handling high speeds on curves, and I had some 600s I think, on the Camry that only lasted 30K miles, which the 400s and 320s did as well.

UTQG Temperature Grade
Temperature Grade is for all practical purposes is a speed rating. It indicates how much heat is generated by the tire. If it can't get rid of the heat fast enough it will fail. For example the C rated tire running at 115 F would most likely fail due to heat build up, but maybe not if the ambient temperature was only 35 F. Maybe the B one would fail at 112 mph in a 130 F Death Valley afternoon.

A Over 115 mph
B Between 100 to 115 mph
C Between 85 to 100 mph

There are also AA, A, B, and C, UTQG traction grades, and on LT tires C, D, and E ratings that indicate the number of plys used in the tire's construction, 6, 8, and 10 ply respectively.

European Speed Rating, (in mph).
Q- Up to 100mph BFG AT KO LT285/70/17
R- Up to 106mph
S- Up to 112mph
T- Up to 118mph Bridgestone Dueler Revo P285/70/17
U- Up to 124mph
H- Up to 130mph
V- Up to 149mph
W- Up to 168mph
Y- Up to 186mph
Z- 149mph and over

That answered that ..... did you come up wiyh all of that off the top of your head?

__________________
'04 SexySilver KC XE ....120k miles....the usual mods.

Researched most it tonight because I was curious. I knew the LT ply rating part and knew 420s were supposed to last longer than 320s, but had forgotten what unit the 420 was. Speed rating I had posted recently and knew it for the all terrains I had mentioned, BFG and REVOS. The ABC stuff I rememberd had to do with speed but was confused by temperature. The 35 F and 130 F crap I just made up.
.