I know modern ones are prety acc esp at low speed and it seems errors increase with speed.
Im wondering how acc is my 28 year old Celica?
I know the ST version came with naff sized wheels but my GT came with wolfrace alloys, the same thing applied to my 79 Celica ST/GT 13in or 14 in rims.
Would my speedo be acc for a car of its age, and i couldnt see them back in teh 70's putting a diff cable on for ST/GT diff sized wheels.
ta
"Julian 'Penny for the guy' Hales" wrote in message news:80jId.189522$ snipped-for-privacy@fe1.news.blueyonder.co.uk...
borrow a gps unit and test, the variation in wheel size is usually accompanied by profile changes to the tyre so the circumference doesn't change a lot.
from new the accuracy only has to be: at 30 mph minus nothing or plus 10 percent.
mrcheerful
No cig lighter, or power leads for radio etc, stripped inside. plus i cant think of one person who has GPS.
>"Julian 'Penny for the guy' Hales" wrote in message news:80jId.189522$ snipped-for-privacy@fe1.news.blueyonder.co.uk...
Time it on the motorway. Get a friend/spare child with a stopwatch (my phone has one built in) and time the car over a couple of miles using the little posts with telephone symbols on them. They're 100m apart. Pick a couple of speeds which you can maintain safely i.e. don't do 30.
"Julian 'Penny for the guy' Hales" wrote in message news:80jId.189522$ snipped-for-privacy@fe1.news.blueyonder.co.uk...
Go past a speed camera at an insane speed. Take a note of your speedometer reading when you see the flash. Compare this to the NIP reading. Takes a week or two to get the result tho, but it is cheaper than buying a GPS unit.
>
worth a try thanks
Tyre manufacturer web sites often give-out the rolling radius/diameter or number of revolutions per mile as part of the tyre specs.
So - if you can find this information for the original size and profile tyres, and for the tyres you now have fitted, that might give a guide...
"Julian 'Penny for the guy' Hales" wrote in message news:80jId.189522$ snipped-for-privacy@fe1.news.blueyonder.co.uk...
Worth a try.
I went from 205/60 14's to 195's due to scrubbing on arches if i have passengers. Not level of grip diff noticed.
ta
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