The second or third time out you have some clue about what you're doing, find yourself within a week and a half of the racing line, and so you get to thinking about how you're progressing against the clock. Next comes a download of Harry's Lap Timer or the like. (Whoops.) You might also look around the paddock to see what the advanced crowd is up to. It doesn't hurt to look…
And now you're here. Because you've identified the one commonality across the wide range of advanced track day vehicles as track (R-compound) tires. You probably need some of that utterly nonessential hobbyist rubber in your life.
Plus your performance street tires are shot anyways.
Track tires are, without question, the most straightforward and effective performance upgrade for track day/HPDE purposes. R-compound track tires offer measurably superior longitudinal and lateral traction, and therefore improved lap times.
Car and Driver magazine recently caught some flack from informed readers when they track tested the Alfa Romea Giulia Quadrifoglio against rivals fitted with less proficient performance rubber.
The Alfa wears sticky Pirelli P Zero Corsa tires -- an "innovative racing compound" per Pirelli. The competition was shod with the very capable, but less track focused Michelin Pilot Super Sport (PSS).
As a follow up to that group test and to address the grievances, C&D swapped the Corsa's on the Alfa for the Continental ExtremeContact Sport (a maximum performance summer tire and PSS equal), and ran performance tests.
Lateral traction was also measurably superior. The Corsa's facilitated an even 1 g around the skid pad, while the ExtremeContact Sport managed 0.96 g.
The test numbers provide insight as to the track tire experience. The traction offered by R-compound tires is just plain superior in every way. You sense it in the brake zones, corner entry, mid-corner, on corner exit; everywhere other than the grassy run-off area.
In our experience, the lap time gain of an extreme performance summer tire like the Hankook Ventus R-S3 as compared to a top tier performance street tire is about 2 seconds (at a track 2.1 miles in length).
An even more track focused streetable track and competition tire (in Tire Rack parlance) such as the Pirelli P Zero Trofeo R will slice another 1-2 seconds off.
And the gain with full race tires/slicks? Here's insight from HoosierDirect.com:
"When compared to the “ultimate” or “extreme” performance summer tires offered by all the tire manufacturers, DOT R-compound tires provide significantly more dry traction which results in lap times that are 3-6 seconds quicker when installed on similarly equipped track cars and significantly faster lap times for cars that have been setup to take advantage of the sticker compound of the r-comp track tire."
So if you've hit the limitations of your performance street tires and your driver skillset has advanced sufficiently, expect a significant lap time advantage with any variety of track tires. Just make sure you've got the brakes to accommodate the improved traction.
For further information and guidance see Track Tires vs Performance Street Tires.