Get a tire tread depth gauge

One of the most expensive aspects of owning a high-end sports car these days is buying tires for it. Anyone that has priced a replacement set knows that you might spend $1500 for new Michellin Pilot Sport 2s. This makes tire health a factor we should pay attention to, making sure our alignments are correct, inflation is correct, and that wear is occurring evenly.

You can stand there and stare at the tread, or you can measure tread wear across the face of the tire, and note progress over time empirically. The proper tool is cheap too, and anyone that can put air their tires can use one. Just order one these:

Amazon.com: Milton S448 Tire Tread Depth Gauge: Automotive

Yup, all of $7.

5000 mile update - I just measured 7.5/32" of tread depth on both rear tires. The PS2s have 10/32" new, so I've run through about 25% of the tread, in 5000 miles of very conservative driving on mostly asphalt roads. Assuming I replace them at about 2-3/32", I should be getting about 15K miles out of the rears. Not great, but not horrible. That's about the same as I've got out of all of my sports cars with Y-rated tires. The only exception was the Pirelli P-Zero Assimetrico, that yielded only 9K miles on the rear of my M Coupe.