some tire size infor r.e. recent tire ?'s

[MidLifeSpeed]

FYI ...
All measurements in inches

Base Camaro (Secretary's special)
tires 215/60/16
width = 8.46
Diameter (tire+wheel) = 26.157
Circumference = 82.176
tire rpm @ 60mph = 771.028

235/55/16
width = 9.25
Diameter = 26.177
Circumference = 82.237
tire rpm @ 60mph = 770.456
indicated speedo = 59.95 mph

245/50/16
width = 9.65
diameter = 25.646
circumference = 80.568
tire rpm @ 60mph = 786.416
indicated speedo = 61.20 mph

255/50/16
width = 10.04
diameter = 26.039
circumference = 81.805
tire rpm @ 60mph = 774.525
indicated speedo = 60.27 mph

so none of the common tire size changes for 16" wheels really makes much difference in speedo calibrations ...

[Jack]

Excellent info. I wonder what the effect on the turning radius is with the 255's as opposed to the 215's? I would expect it to be less, any thoughts?