my 2015 SSV redline Speedo error, got speeding ticket!

[theburna57]

Not necessarily....It goes by rolling radius....ie say you go from a 225/60X16 to a 245/45X18, the rolling radius will be identical, which means the speedo stays the same....Or if you go from 245/45X18 to 245/35X20, the rolling radius stays the same.

These sizes I have posted up are all VF Commodore factory sizing

But if you go from a standard 16 to a non standard 20, as they wear, the speedo reading will step out at a greater rate than a 16

 

[Just Damo]

My gps reads 97 - 98 when the speedo reads 100.

Stock rims and tires I'm 3-4 under, 56 @ 60kph. I read that figure off my dashcam tho, not sure if there is a difference really

 

[vc commodore]

But if you go from a standard 16 to a non standard 20, as they wear, the speedo reading will step out at a greater rate than a 16

It goes by rolling radius....In other words, providing the overall height with tyres fitted to both rims, the speedo will read correctly....And VF Commodores came standard with 16, 17,18,19 and 20" rims, so the over all height of all these will be close enough, that the speedo reading will always be under or on the actual road speed