Racing tires vs street

BGTV8

At the limit, on most tracks, and r-spec tyre will generally give you around 2 seconds. Someone in this thread has already made he comment about time in the lap spent grip-limited and that is where you gain time.

When I say "r-spec" I refer to a competition tyre that is DOT approved. R888, NT01R, DZ03G, RE055S, A050 etc. These are all treaded, race construction with race compounds. Most carry DoT approval and "can" be used on the road (but why would you - they are usually so soft that they would wear out in 500kms).

There is an addiitonal full-race slick which is purpose designed for racing and which are not DoT approved for road use and can only be purchased thru specialty suppliers.

The gap, same car, same driver, same circuit, same day, same conditions is usually ~ 2 seconds from premium road tyre to R-spec and 2-3 seconds for full race slick.

Personal experience on my race car (not the Z34) betweeen Dunlop Motorsport slick (290/625R16) and DZ03G or Kumho V70A (265/45R16) is 1.8 secs/lap at Sandown International Raceway but Sandown is point and squirt - Philip Island has 4 very high-speed corners (entry well above 200kph and mid-corner 200+) and the gap is more like 2.5 to 2.6 seconds.

Check out KF365 in the Aussie ZClub forum for difference between OEM to DZ03G at various circuits and you wil get the idea.