tolerances of SPECS

lozza23_uk · 6 Aug 2006 at 19:46

not sure what APCO guidelines are...but there is a 10% tolerance (as others have said) on the instrumentation in your car, which includes the tyre pressures right to the quality of the gauge.

you must remember that the tiny little speedo gauge in your car can show a range of 120-160mph!
that is a huge range for such a small gauge. hence the tolerance allowance.

this doesnt mean you can drive at 33mph indicated on your speedo through a gatso or specs though..because your car might actually be doing 10% more than that!

DannyDan · 6 Aug 2006 at 19:48

lozza23_uk said:
this doesnt mean you can drive at 33mph indicated on your speedo through a gatso or specs though..because your car might actually be doing 10% more than that!

I thought speedos weren't allowed to under-read?

Jokester · 6 Aug 2006 at 19:52

DannyDan said:
I thought speedos weren't allowed to under-read?

That's my understanding as well, something to do with the requirements of being road legal in the UK. As such all speedos over estimate your speed to make sure of it.

Jokester

Fr0dders · 6 Aug 2006 at 20:34

lozza23_uk said:
this doesnt mean you can drive at 33mph indicated on your speedo through a gatso or specs though..because your car might actually be doing 10% more than that!

not likely

speedos nearly allways overread.

Jokester said:
That's my understanding as well, something to do with the requirements of being road legal in the UK. As such all speedos over estimate your speed to make sure of it.

Jokester

i can stand corrected on this, but iirc theres no check for this in the MOT. so much so, that 5th gear even did a feature on it, showing why zero tolerance with speeding was unfare. They got some old bangers, some GPS eqipment, and showed how they under/ over read

allmost all over read, but at some speeds (usually higher) and on some cars, the speedos under read

but im sure they said there was no check for this in the MOT.

DannyDan · 6 Aug 2006 at 20:40

MrLOL said:
but im sure they said there was no check for this in the MOT.

AFAIK the speedo isnt checked at all in the MOT, you could pass with a non-functioning one.

MaXXeH · 6 Aug 2006 at 21:20

i asked some copper about this when i was out on the town semi drunk and he said it is 10%

Freefaller · 6 Aug 2006 at 21:28

I just stick to the indicated speed - it's far easier than worrying about it. I have to say the the SPECS system is far more sensible - even though I hate slowing down

I think as general rule as stated the 10% + a few is a generally accepted rule - but I don't take the risk.

I do love when the SPECS zone ends though and you can nail it

Matt82 · 6 Aug 2006 at 21:33

same here, but i just worry about whats going through the heads of the ppl behind me flashing their headlight and getting angry at me holding them up.

at night its not easy to see when the initial set of cameras start.

Freefaller · 6 Aug 2006 at 21:36

Matt82 said:
same here, but i just worry about whats going through the heads of the ppl behind me flashing their headlight and getting angry at me holding them up.

at night its not easy to see when the initial set of cameras start.

Maybe they don;'t realise how they work and want to blast past you?

Fortunately SPECS is where my B2 comes into it's own - it really helps for those things.

Matt82 · 6 Aug 2006 at 21:38

i was on the M25 at about 1am on saturday, clearly it was dark. i had done the same stretch about a week earlier so knew the SPECS were there, but in the dark it was not obvious where the system started, so as soon as i saw "average speed cameras" i just went straight to 40