Tires

This is not a truck or truck tire question but, I'm going to take a stab at it anyway. No matter what kind of vehicle you drive, if you don't think the spedometer is correct, it is fairly easy to check. Nearly every highway in North America has markers every mile. Find a friend with a watch with a second hand. Take him or her on a ride down an uncongested piece of smooth, flat Interstate highway (or any limited access highway). Hold your speed at a steady 60 MPH. Have your friend look at the watch as you pass a mile marker. It should take exactly 60 seconds to get to the next marker. If you consistantly reach the next marker in less that 60 seconds, your speedo is reading too slow. If it take longer than 60 seconds, your speedo is reading too fast.

Most people have a tire and wonder what size wheel they need. You seem to have things reversed. I would think there could be many sizes of tires that could fit, the real issue is what will fit under your wheel wells without hitting anything. To answer that, I would consult your car or truck dealer to be sure.

It pays to be old. I called a retired Goodyear tire design engineer I know. Just by chance, he happens to be one of the people who designed this tire. The date code on your tire indicates that it was made during the 24th week of 1968 (the 248 at the end of the DOT code). I figured it had to be either a 1968 or 1978 tire and the original designer confirmed that it would have to be 1968.

Treadwear depends upon road surface, speed, load, tread design, tread depth, temperature, weather conditions, driver style (acceleration, braking and turning) and terrain plus a few things I probably have forgotten. If anyone can come up with a formula using all these variables, Goodyear will hire him in a flash.

U.S. DOT Tire Identification Number...
This begins with the letters "DOT" and indicates 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 3105 means the 31st week of 2005. The other numbers are marketing codes used at the manufacturer's discretion. This information is used to contact consumers if a tire defect requires a recall.