265/35/18
Original tire
Sidewall: 3.65 in
Radius: 12.65 in
Diameter: 25.30 in
Circumf: 79.49 in
Revs/mile: 797.06
275/30/19
New Tire
Sidewall: 3.25 in
Radius: 12.75 in
Diameter: 25.50 in
Circumf: 80.10 in
Revs/mile: 791.03
225/40/18
Original tire
Sidewall: 3.54 in
Radius: 12.54 in
Diameter: 25.09 in
Circumf: 78.81 in
Revs/mile: 803.94
235/35/19
New Tire
Sidewall: 3.24 in
Radius: 12.74 in
Diameter: 25.48 in
Circumf: 80.04 in
Revs/mile: 791.64
Based on these specs, if any boxster owner can discern a significant difference in ride quality based on this slight reduction in actual tire sidewall, then that person should be working for NASA . For anyone who can appreciate the dramatic improvement in handling and overall performance that I experienced by eliminating nearly 100 lbs. of unsprung rotational mass from my vehicle, then I'll buy you an ice cream.
