Thursday, January 28, 2010

My tires exploded

About a year ago there were stories in the news about people having old tires on their cars and how the tires age, even when not in use, and become unsafe. I filed it away for forgot about it. About a month back the story was back in the news. I did some research and started attempting to look for DOT date codes on our antique cars.

First car. Our 1969 Mustang coupe. I put four new bias ply tires on it. In about 1984! I remember bias tires were hard to get even then. Radial had taken over. The date codes on these four Goodyear’s, didn’t even have the same format as the write ups for checking tire age. Given they were put on 26 years ago, and might have been two to four years old then, it was time for new shoes! The spare tire in the trunk was also a Smithsonian-worthy relic. It was a “Buccaneer” tire that I think was a gas-station brand. I think my dad put those on around 1974. I was tempted to hit it with a hammer and see if it would shatter.

Second car. Our 1970 Mustang Mach 1. I restored that car in the early 1990’s. The tires on it are Goodyear reproductions of the original bias-ply tires. But this is 2010, so even those tires are 16 years old.
Neither of these cars is driven all that much, maybe 1000 to 2000 miles a year, so the tires never wear out. But they start getting hard, small cracks appear in the treads and such.

So on one of my Car Forums I query about peoples tire age. One guy reported that his 15 year old tires started coming apart at 35 MPH in his neighborhood and he had trouble getting it parked, even at that slow speed. I tend to get mine out on the freeway by us and get up to 70! A tire issue at that speed would mean a crash and possible a totaled antique car. The recommendation on the Mach was to take off the reproduction tires, coat them with a quality rubber protectant and store them under a blanket in a cool and dark place. Use them only for big shows where “original” counts. I took that advice. I purchased four BF Goodrich Radial and four brand new Magnum style rims.

On the coupe, I just purchased five radials. It isn’t shown that much and the original type tires, are not even reproduced.

The most fun was attempting to figure out just what tires would fit these old cars. The coupes original size was “6.95X14”. Those types of specifications were going away in the late 1960’s and 1970’s. The Mach is an example, as the original size is “F70X14”. Except that nomenclature also went away when they went to metric and then P-Metric, and whatever they are at now.

We wound up with a 205X70X14 on the coupe. That is a bit fatter than original, but about the same height as stock. We went with a 235X60X15 on the Mach. Seems to be what most of the Mustang parts houses and individuals get to fit. Those are a bit shorter that stock, but wider also. Plus, they look great.

The top picture is the coupe up on jack stands in our shop. All five wheels were getting new soles.
The bottom photo is the Mach. You can see the original tire still on the car and the new Magnum wheels and tires stacked up awaiting me to switch them out.

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