Dear Tom and Ray:

When I was learning to drive in the '50s, there was a rule to not drive above 40 mph on the highway for 10 minutes in order to give the bias-ply tires time to warm up so they wouldn't be overstressed. Is there a similar rule for today's radial tires?

-- Claude

TOM: Well, I learned to drive in the '50s, too, and I don't remember any such rule.

RAY: Not the 1850s, you dope. The 1950s! When my brother was learning to drive, wheels were wooden, and the biggest concern was getting splinters when you changed a tire!

TOM: The answer is no, Claude. There's nothing you need to do to warm up radial tires. They can be driven at highway speed immediately.

RAY: I don't even remember any rule about warming up old, bias-ply tires. I know that if bias-ply tires sat for a long time, they could develop flat spots. And then you'd have to drive them for a while to work out the flat spot so the tire would be perfectly round again. Maybe that's why you were advised not to run them at high speed right away?

TOM: Or perhaps your father just wanted to keep you from driving fast for an extra 10 minutes, Claude.