Speedometer

[LA-LA]

The real speed and the needle on the speedometer have always a tolerance.

We tested with GPS with two "not holded back by the v-max limiter" iQs. One with 15" and the second with 16" wheels.

Max is showing the max tolerance by law.

Our fastest speed was 123 miles/h on flat German Autobahn.

198 km/h means the needle is pointing 210 km/h (130 miles/h)

[s44gtw]

You say you checked with 15" & 16" wheels,

were these fitted with standard size tyres 175/65R/15 & 175/60R/16

or was something different in size fitted?

There is a difference in 'rolling radius' with the standard 16" over the 15" tyre, as in they are bigger on paper,

not compared them side by side or with an actual tape measure tho.

In the case of your test the tyres were obviously of a different rolling radius.

This online converter shows for the 2 sizes above .4 MPH difference at 30mph from the bigger tyre

& .8mph @ 60mph.

(i suppose @ 120 MPH you can expect the difference in reading to be about 1.6 mph or so.)

The graph on your post appears to show pretty near double those figures given on the online converters..

You can get a difference when checked by GPS with a higher tyre pressure & cold tyres etc.

http://www.kouki.co.uk/utilities/visual-tyre-size-calculator

george

[LA-LA]

Thanks george

the diesel version has the standard 175/65R15

and the 1,33l version has the standard 175/60R16

means a rolling radius ~ 191-193 cm normally a difference of 1,3%.

only at our highest speed both iQ have the same needle/speedometer "number"

br

LA-LA