Moving from 14" steel to 16" alloys, speedo?

[AhmedRSi]

Whats the likely change in the speedo accuracy, does it go higher than what speed your actually doing or lower?

eg will it read 27 at 30mph or 33 for example

also, will it make much of a difference? I mean a 5mph fluctuation at 70mph is a reasonable change i would think.

 

[DougClio16v]

It's within the 2" safe limit. The speedo will hardly change.

You won't feel anything apart from better grip on the road if you width is bigger.

 

[Pep]

depends on the rolling radius, calculate the height of the profile on both tyres, and add thsi to the diameters and see which is bigger, you can also calculate the diameter and work out circumference.

 

[bmh.01]

http://www.miata.net/garage/tirecalc.html

 

[AhmedRSi]

Speedo is 2.1% too slow
When your speedo reads 60mph you are actually travelling 61.2 mph

So, bearing in mind that when my speedo said 60 i was probably only doing 58/59 anyway due to speedos just bieng slightly overrated, i will notice no difference?

Thanks for the site.

 

[Gumby]

Most cars over-read by about 3-4mph anyway don't they?

 

[AhmedRSi]

Thats what i thought.

 

[philmots]

yeh when im doin 80 the nav reads 76/77

 

[philmots]

^^^ or even, when im doin 76/77 the speedo reads 80