Does a change in total diameter affect the speedo?

yes definately

That's what I thought.

Seeing I am gettin' on a bit and have almost qualified for a hat, it wouldn't do to be booked for speeding, now would it!

I'll just make do with the basics, leave all the fancy stuff for the cat in the hat.

you can get the speedo recalibrated but to make sure it reads right. It wouldn't be that much out anyway.

It actually makes me laugh and reminds me about in Vic when they brought in teh 1km/h tolerance for there speed camera's. According to ADR's a speedo on a brand new car can be out by 10%. If you were doing 100 and your speedo said 100 you could be doing 110 - I was amazed noone took it all to court.

Here's all the crunched numbers for you - all figures are compared to the Classic 195/65-15:

Spec---------Sidewall-----Radius-----Diameter----Circum----Rev/km---Diff
195/65-15---127mm-----317mm-----634mm-----1993mm-----502.....0.0%
205/55-16---113mm-----316mm-----632mm-----1985mm-----504...-0.04%
215/45-17---97mm------313mm-----625mm-----1964mm-----509.....-1.4%
225/45-17---101mm-----317mm-----634mm-----1993mm-----502.....0.0%
235/45-17---106mm-----322mm-----643mm-----2021mm-----495.....1.4%
225/40-18---90mm------306mm-----612mm-----1922mm-----520.....-3.6%
225/45-18---101mm-----317mm-----634mm-----1993mm-----502......0.0%
235/35-19---82mm------324mm-----647mm-----2033mm-----492......2.0%

195/65-15 to 205/55-16
Speedo reading 0.4% too fast - at 100kph you're doing 99.6kph.

195/65-15 to 215/45-17
Speedo reading 1.4% too fast - at 100kph you're doing 98.6kph.

195/65-15 to 225/45-17
Speedo reading the same - at 100kph you're doing 100kph.

195/65-15 to 235/45-17
Speedo reading 1.4% too slow - at 100kph you're doing 101.4kph.

195/65-15 to 225/40-18
Speedo reading 3.6% too slow - at 100kph you're doing 100.4kph.

195/65-15 to 225/45-18
Speedo reading the same - at 100kph you're doing 100kph.

195/65-15 to 235/35-19
Speedo reading 2.0% too fast - at 100kph you're doing 102kph.


If you want a size compared with what you're running now, just shout out!

Gosh you make me laugh Wendy! the information you can get, fairdinkum!
I bet you cant cook
I think you wore that hippi out at Bathurst, he's been quite ah!

Bet you I can!!!!

Either the child bride has got him working double time or his old-timers has kicked in and he's forgotten we're even here. It must be fun for someone his age - come into a place like this and make the same "new friends" every time!

Yeah I'm runnin...................