Le Mans markings, eg the dots of 1967

At LeMans in 1967 some, if not all, of the prototype cars appear to have yellow and/or red makings at various places on their bodywork. These markings are round "dots" about 3 or 4 inches in diameter and the winning Ford MkIV, for instance, appears to have had two yellow dots on the top immediately behind the upper corners of the windshield, and a red dot (hard to see on a red car) on the rear bodywork between the rear window and the left rear tire. They are also visible in photos of the Ferrari P4's and Chaparral 2Fs. I'm assuming that they were there to satisfy some regulation of the ACO, but what were they for and why just 1967?

The dots were to help the safety/fire crews know what material the body panels were made of, so the marshals could properly fight any potential fire. Red dots indicated fiberglass, yellow dots indicated aluminum. Supposedly, the Shelby team put red dots by mistake on the aluminum roof of the yellow McLaren/Donohue Mk4, and then tried to correct the error by rubbing them. The color changed to orange...no doubt further confusing everyone.

Thanks. I've always wondered about those dots.

This has been discussed before in another thread and the general consensus was as set out in teegeefla's response. These dots appeared in earlier years as well, I think from 1962 onwards. Another car that blows the yellow = aluminium, red = fibreglass theory is the class-winning Lotus Elite in 1963. I'd be inclined to put that down to a similar mistake to that made by the Shelby team, unless anyone would care to venture another opinion....

Be careful not to confuse the spots with the 'RAF-type' roundels or concentric rings used in the early fifties to mark cars that were eligible for the Rudge-Whitworth Bienniel Cup.