What is it? CXXVII

Maybe those calipers were being carried in the blimp. ;-)

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I thought it might be for measuring baseball games or symphonies because it was divided into ninths. I wonder how that applies to tires.

Yeeeears ago, in the years leading up to about 1972. a very common sized tire was an 8.25-14. Meaning the tire was approximately 8.25" wide depending on the manufacturer and fit on a 14" wheel. The sizes typically went from, 5.60-15 for the Beetle, to 6.00, 6.50, 7.00 7.35, 7,75, 8.25.

8.55, 8.85, 9.00, 9.15 . This gave way to the tire sizes that included the letter and the aspect ratio. The 8.25-14 became a G78-14, 8.55-14 became a H78-14, 9.15-15 became an L78-15. That last larger sized tire was common on large Continentals and Cadillacs. Later the P metric sizing for passenger car tires was introduced in around 1977. The G78-15 became the P215-75-R15. The P indicated a passenger car rated tire, the 215 indicated that the tread was 215 mm wide and the side wall was 75% in height, as the width of the tread, the R stood for Radial and again the 15 was how many inches tall the wheel was. With those numbers you can determine how tall the tire is. Side wall width 75% of 215 mm X 2 + 15". 27-3/8" tall.

As for the gauge, I guess it was used so that the tire salesman did not have to memorize the conversion when replacing an old 8.25-14 tire with the newer standard of tire measurement. The gauge would have measured a G on its scale for tire width.

"Leon" wrote in news:yVaDg.272$ snipped-for-privacy@newssvr13.news.prodigy.com:

And big trucks and trailers (like semis) used even bigger - 10.00x20; a ten hundred-twenty. The tread was 10 inches wide and the rim was 20 inches in diameter. God, I've busted *so* many of those down by hand - split rims - using unly a wedge hammer and a pair of irons. I'm glad the industry finally got away from those and the split rim 16.5" wheels. I've seen retainers for spit rims come off under pressure and do amazing damage. I ALWAYS used a safety cage. Sorry....got away from woodworking for a second there, I'm back now.

I don't understand why the gauge has nine divisions between each letter and the next.

I have never seen one myself, however as I previously mentioned, different manufacturers started at slightly different locations of the tire to determine the width measurement. Most tires back then had a rather inconsistent tread design that sometimes wrapped around to the sidewall vs. having a clear start and stop point for determining where the tread and sidewall ended. I would suspect that the graduations would help the reader take into consideration tread that appeared wider and or perhaps to help determine if the next up size could be used. Measurements may have been taken at multiple points on the tire.

Yeah it was a little dicey when filling the ten hundreds with split rims and waiting for the beads to pop. While our store was relative small and did

99% passenger tire business we did get the occasional split rim. We had no tire cage for airing up the tire so we laid the tire and wheel under a lift and powered the lift down on top of the wheel and tire when airing up.