how to calibrate NAvi plus retro fitted!

Having problems with the navi i think it does need calibrated before i use it??? am i right ie for my 19's wheels and that!

ive connected the speed sensor and illumination wires and put the disk i recived in, the 2004 map disk with british maps, and the navi works i have about 6 GPS satilites on at a time, sumtimes 5 and sumtimes 7.

my problem is it takes a while to update my location about every 45sec - minute, and some times doesnt update althought on checking i still have my satilite reception,

I have no operating or calibrating instructions! its got me confused!

What can/do i do??

P.s she never tell me to take any turns etc! /ubbthreads/images/graemlins/beerchug.gif

tried the tyre size input again mike and still no further forward, but when i conected the speed sensor wire to pin 21 in the cluster wires it was blue/white not black and white is this correct i cant find any other installation instrcutions on the web!

thats ok then, so how do i check iive got the signal there??
apart from the obvious its now working! went thorough the wiring again! looks ok!

i didnt need to remove any wires on the installation did i?? i could be getting false inputs sumwhere!