Tire Diameter Affect on HP TQ? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

beauwalnut · 08-05-2013, 01:25 AM

I gotta start of by saying I DID search and found almost nothing...

Has anyone tested the performance attributes of various tire diameters?

Gears, cams etc. are designed with stock wheels/tire diameter in mind. In a 240 that is roughly 24 - 25 inches
Stock S13 195/60-15 have a diameter of 24.2"
Stock S14 205/55-16 have a diameter of 24.9"
(Per: http://www.federaltire.com/download/specFD1.pdf )

My theory:
If over sized wheels/tires hurt 0-30, under sized wheels/tires should help 0-30. This would make all gears "lower" so the engine is revving higher at the same gear. Making a car better at time attack... or zipping around town. I am thinking 195/45R15 or 215/35R16 both @ 21.9"

Any Zilvians tried this?

08-05-2013, 01:25 AM	#1
beauwalnut Join Date: Oct 2012 Location: Orange, The Really Real OC Posts: 32 Trader Rating: (1) Feedback Score: 1 reviews	Tire Diameter Affect on HP TQ? I gotta start of by saying I DID search and found almost nothing... Has anyone tested the performance attributes of various tire diameters? Gears, cams etc. are designed with stock wheels/tire diameter in mind. In a 240 that is roughly 24 - 25 inches Stock S13 195/60-15 have a diameter of 24.2" Stock S14 205/55-16 have a diameter of 24.9" (Per: http://www.federaltire.com/download/specFD1.pdf ) My theory: If over sized wheels/tires hurt 0-30, under sized wheels/tires should help 0-30. This would make all gears "lower" so the engine is revving higher at the same gear. Making a car better at time attack... or zipping around town. I am thinking 195/45R15 or 215/35R16 both @ 21.9" Any Zilvians tried this?