Speedometer is MESSED up - what do i do?

VwPo1o · Post by **VwPo1o** » Fri Mar 26, 2004 11:58 pm

As you may or may not now, i recently took the big leap of going to 17's from a set of 14" babies, and my speedomter is f***** up. The speedometer and the clock shows about 90% of the true value. What can i do to fix it and how much will it cost?
Thanx

polo2k · Post by **polo2k** » Sat Mar 27, 2004 1:53 pm

by down-sizing the tyres when you go to 17" yo ukeep a 'true' reading and therefore by up sizing when you go back it should remain true.

VwPo1o · Post by **VwPo1o** » Sat Mar 27, 2004 7:40 pm

But doesn't the circumference of the wheel still change when you go up to 17. I used to have 185/55/14 tyres and now i have 205/40/17 tyres. The circumference of the old tyres is roughly about 94% of the new ones. So surely all the readings are less than what they are supposed to be. On the way back home yesterday from uni, i compared my clock readings to the distances on the motorway.
Eg, the sign would say that there was 12 miles left to the service station and my clock ended up saying 11.2, which is roughly 94%. Sounds right!

pettsy · Post by **pettsy** » Sun Mar 28, 2004 12:44 am

this might be of some use...

http://www.tyresave.co.uk/tyresize.html

Speedlaw · Post by **Speedlaw** » Sun Mar 28, 2004 11:22 am

Just to clear it up, even with the skinniest tires on 17's, the reading will still be off- as you said.

Try 195-40-17's, or consider adjusting the odo (if that's even possible).