speedo adjustment

I fitted some low profile tyres to improve the handling and acceleration a bit, only it now shows 16.5miles on a 15.8 mile trip - about 4% less mph so maybe save me getting a fine on the speed cameras if nothing else!

There were some wrong van tyres fitted to it before that were way to big (195/65) and the car went just awful.

I prefer the improvement to the car even if nothing can be done but I wondered if there was a fine adjustment possible (ECU or something) to allow for the range of tyres 14", 15" and 16" that can be fitted to a C3?

Hi.

There is no fine tuning for the Speedo available or necessary.

The cars fitted with lower profile tyres are matched to a bigger diameter wheel so the circumference of the tyre stays the same and the Speedo calculation is correct.

Arfur Dent wrote: ↑Thu Jan 16, 2020 2:14 pm Hi.

There is no fine tuning for the Speedo available or necessary.

The cars fitted with lower profile tyres are matched to a bigger diameter wheel so the circumference of the tyre stays the same and the Speedo calculation is correct.

I thought it was a silly question but there is some variation between the different tyre aspect ratios and rim sizes specifified for the car so I thought the manufacturer must provide a way of compensating as the pickup is from the abs ring which is fixed but maybe the variation <2% is less than worth bothering with.