I got booked a few weeks ago, cop said I was doing 115kph and the speedo said I was doing 93kph when I looked at it. (I looked because I saw the cop coming up behind me) this was in a 100 zone. I did not admit I was speeding but I did say that I thought the cars speedo was out. I got booked for doing the 115kph the cop claimed. He also pointed out the 16" wheels on the car. I think this is what got his attention, gen2's with mags are pretty rare around here

Today I took the Magna down to a workshop in Tamworth (200km from home) which has a Dyno and certification for speedo tests. at 100kph on the speedo my car read 101kph on the dyno. Someone must have already recalibrated the speedo in my car :D It's a 4cyl TR with 205/60-16's on it.

It will be interesting to see how this goes in court, It's going to be expensive if i'm not successful :redface:

thats interesting to know coz my 4cylinder TR also has 16's on it and ive often wondered how much my speedo would be off by.

good luck with your case anyway.

Good to know your speedo is accurate... but in the court case it comes down to...

How can you prove you were doing 93...
How can he prove you were doing 115...

Your car would have had 185/75-14 as the stock dimensions for the wheels.. And because the wheels were upgraded to 16" theyd need different tyres to compensate, which was done, as u stated they have 205/60-16..

If you have a look at this site http://www.miata.net/garage/tirecalc.html
and plug in your numbers.. youll see that with the new wheel size and the tyres that are on them, your speedo would be out by 3%.. so at 100km/h you'll be going 103.. which isnt a great deal of difference. So its doubtful your speedo was re-configured, cause as far as i know its an expensive thing to do.

But yea, you definately werent going 115 cause of the tyres..

So when you go to court, im assuming your not going to tell them that your speedo isnt incorrect?

Tell em you werent aware that the increase in tyre rim size was affecting the speed, and you recently purchased the car (assuming you have) take receipts if any, and pictures, and tell them you simply had no idea. And that you have taken the car to get re-calibrated (just show em the receipt for the dyno place). Hopefully theyll see it as a mistake that wouldve needed to be fixed eventually.

anyway keep us posted on what happens

EDIT: If you want to avoid being over the limit, when you go to buy new tyres get 205/55-16 that leaves you going 0.2% slower, which is the closest youll get to the real speed :D

Hope all this helps

thats interesting to know coz my 4cylinder TR also has 16's on it and ive often wondered how much my speedo would be off by.

good luck with your case anyway.


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

yeah I use the tyre calc often (it's in favourites) and according to the calc the 16" wheels and tyres on it were out by about 5% from standard. I was very surprised the speedo was so accurate. By the way, when the court papers arrived the alleged speed had dropped from 115kph on the side of the road to 111kph.

unfortunately I can't pleed ignorance on knowledge about defects in court....i'm a licenced mechanic. I intend to use the dyno print out and the witness that was in the passenger seat to corroberate that I wasn't doing over 100kph at the time I was stopped as alleged.

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


LOL lol lol lol
mines off by miles. serves me right for getting the mag and trye package i did.
i have bridgestone turanza's 215/65R16. and yes i know they are huge.

nfortunately I can't pleed ignorance on knowledge about defects in court....i'm a licenced mechanic. I intend to use the dyno print out and the witness that was in the passenger seat to corroberate that I wasn't doing over 100kph at the time I was stopped as alleged.
Make sure that they have to get the officer up on the stand. As for doing 115 or even 111 when the speedo says 93 you would have to have some stupidly oversized tyres to get that and you obviously have the right tyres. You weren't doing over 100 prior to that?

I think you will be hard pressed to win in court with no other eveidence expect a in car witness and a dyno read out.

Whats the fine for 15k's over? I'd just take the fine rather than going to the expense of court.

Ash, I sort of agree with you and I was undecided, whether to pay it or fight it. Once i saw that the speedo was actually accurate then i knew for fact that i was doing no wrong as alleged I decided to go to court. The cop saw me overtake and exceed the speed limit about 5 mins before he booked me, he commented about this and that he thought I was doing 121kph as I overtook (this can't be enforced in court as it is a different offence and I havent been charged with it) and he also claimed that the car I passed was doing 100kph on the dot. (I had the other car doing 87kph and had followed it for a few k's. when the cop saw the overtake he was standing beside his car bonnet with nothing in his hands and nothing on the bonnet but he claimed to have a speed on both of us). When he pulled me up about 5 mins later he was quite clear thet the alleged speed he booked me for, was my speed in the few seconds prior to stopping me. also i was fined through a penalty notice not a radar/lidar notice like the day before :badgrin: (i paid that one, it was fair)
If I put the cop on the stand then I will have to pay his wage for a day and 140km travel on top of the court costs and fine if I lose.

BTW. Why can you get booked for speeding within 10% of the speed limit (speed cameras)when this is the allowed variation for a speedo in the ADR's (aussie car design rules)

isnt the fine for doing 11-13km/hr over $100 and 1 point? if he is doing u for 111km/hr in a 100km/hr zone, thats 11km/hr over. :S i know this well

and if the cop didnt have a speed camera to document ur actual speed, him saying ur alledged speed should get thrown out of court. u cant take someone to court on an assumption. u need evidence. if u didnt break the law after u overtook the car while the cop WAS following u and recording speed, i dont c y u should need to pay anything. fight it.

just like the guy that owns the skyline did wen he got chased by 2 cops in plain clothes in a turbo astra on an assumption the skyline would break the law :nuts: revenue raisers

isnt the fine for doing 11-13km/hr over $100 and 1 point? if he is doing u for 111km/hr in a 100km/hr zone, thats 11km/hr over. :S i know this well


What?? in Vic its way higher.. i think on ur P's 15k over and u lose ur liscence..

the fine is $130 and 2 points 1-15kph over in NSW

the fine is $130 and 2 points 1-15kph over in NSW

is that 1km/hr up to 15km/hr OVER the speed limit is $130 and 2 points? :confused:

11-13km/hr is $100 and 1 point up here. (i got flashed doin 12 over, but they sent the fine saying i was doing 11 over ???) good ol QLD ay

is that 1km/hr up to 15km/hr OVER the speed limit is $130 and 2 points? :confused:

Yes! :D

Here in VIC doing less than 10km's over is 1 demerit point, i know just over 10 is 3 demerit points and a $205 fine, i'm pretty sure its either 15 or 20 over and its good bye license (this is for P platers, might be more lenient on full license)

Ash, I sort of agree with you and I was undecided, whether to pay it or fight it. Once i saw that the speedo was actually accurate then i knew for fact that i was doing no wrong as alleged I decided to go to court. The cop saw me overtake and exceed the speed limit about 5 mins before he booked me, he commented about this and that he thought I was doing 121kph as I overtook (this can't be enforced in court as it is a different offence and I havent been charged with it) and he also claimed that the car I passed was doing 100kph on the dot. (I had the other car doing 87kph and had followed it for a few k's. when the cop saw the overtake he was standing beside his car bonnet with nothing in his hands and nothing on the bonnet but he claimed to have a speed on both of us). When he pulled me up about 5 mins later he was quite clear thet the alleged speed he booked me for, was my speed in the few seconds prior to stopping me. also i was fined through a penalty notice not a radar/lidar notice like the day before :badgrin: (i paid that one, it was fair)
If I put the cop on the stand then I will have to pay his wage for a day and 140km travel on top of the court costs and fine if I lose.

BTW. Why can you get booked for speeding within 10% of the speed limit (speed cameras)when this is the allowed variation for a speedo in the ADR's (aussie car design rules)

There is meant to be a % of error for speed cameras. and they need to ping you 3 times on a straight piece of road. but most cops asume your not a solicitor and book you anyway.
you really should of asked to see the radar reading as they have to use a radar and should be able to show you a reading unless they where following for a certian distance. was the car he booked you with a hwy. patrol ?

i really should get around to reading the proper legistration but this is just stuff i've heard from hanging around a solicotors office too much.

There is meant to be a % of error for speed cameras. and they need to ping you 3 times on a straight piece of road. .

I was told they have to hold a reading for over 3 seconds for radar- this was the case the last 2 times I got booked.


but most cops asume your not a solicitor and book you anyway.

Why do cops interpret discressionary powers as the right to bluff and decieve?


you really should of asked to see the radar reading as they have to use a radar and should be able to show you a reading unless they where following for a certian distance. was the car he booked you with a hwy. patrol ?

I wasn't booked by radar I was fined on a penality notice not a radar (speed) notice, there was no radar reading or use mentioned. The cop was behind me maintaining my speed for all of 2-3 seconds, not enought time to correct his speed and get an average speed. It was a hwy patrol car and officer who booked me.

Im not sure about any other state, but from what i have read on MelbCCR (melbourne car cruise registry) police dont have to show you the reading.

the fines in NSW and QLD are so much better than VIC :cry: our fines are heaps more than yours, so you lot shouldnt be complaining.. i think its time to move back to Qld lol

and seems a bit wierd a High way patrol car with out some kind of speed detecting device..

yea well QLD not what it used to be either! got a ticket for 131kmh in a 100 zone 6 points and $350 when i asked to look at the radar he said it was wiped!! go figure