- This 1995 BMW M3 Lightweight is a test car used by Michelin.
- At this year's Lightning Lap track event at Virginia International Raceway, a Michelin test driver ran laps in the M3 equipped with Pilot Sport 4S tires.
- The difference between the coolest run and the hottest run was 2.7 seconds.
We are often asked about the track conditions when we lap. Most of our fast laps at Lightning Lap are set in the early morning when the air is cool and Virginia International Raceway (VIR) is warm but not hot. We can tell by the seat of our pants when the track is slowing; tires get greasy and the cars start to slide earlier. Putting a number on it is hard, though, which is why we asked for help from Michelin's test drivers, who have an almost mechanical ability to drive cars to the same limits lap after lap.
Senior subjective test driver Andrew Simrell brought Michelin's thoroughly used 1995 BMW M3 Lightweight and a stack of Pilot Sport 4S tires to quantify how much lap times change with temperature. In his lapping, he found that from its coolest run (when the air was 72 degrees and the track surface 79) to its absolute hottest (83 and 110, respectively), the M3 added 2.7 seconds to its time.
Simrell needed to slightly baby the 24-year-old test rig and said a new car with an OE Michelin fitment would be more consistent through temperature flux. For those keeping score, Simrell's best lap in the 240-hp M3 was 3:11.6, a tenth of a second quicker than the 330-hp 2007 BMW Z4 M coupe. Modern tires surely contributed to the Lightweight's haste.
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