davey205 7 1 Cars Posted December 5, 2010 Just got myself some 1.9 wheels, will I need to get anything done to fit them such as the speedo recalibrated? Share this post Link to post Share on other sites
Tom Fenton 1,536 Posted December 5, 2010 You'll probably find the speedo is close enough, if you have a sat nav cross check it using this. Share this post Link to post Share on other sites
SurGie 54 Posted December 5, 2010 I would suggest driving past those flashing 30mph speedo lights if possible because i have been in more than 3 cars and the speedo on my tom tom at constant speed is always at least 2mph and at most around 4mph out, the satellite needs time to connect to the sat nav. Share this post Link to post Share on other sites
flipperthebushkangaroo 2 Posted December 5, 2010 Depending on the tyres you fit not much difference try this thing http://www.club80-90syncro.co.uk/Syncro_we...0calculator.htm Roddie Share this post Link to post Share on other sites
harryskid 193 Posted December 5, 2010 I would suggest driving past those flashing 30mph speedo lights if possible because i have been in more than 3 cars and the speedo on my tom tom at constant speed is always at least 2mph and at most around 4mph out, the satellite needs time to connect to the sat nav. Or a speed camera! Share this post Link to post Share on other sites
GLPoomobile 958 Posted December 5, 2010 (edited) I would suggest driving past those flashing 30mph speedo lights if possible because i have been in more than 3 cars and the speedo on my tom tom at constant speed is always at least 2mph and at most around 4mph out, the satellite needs time to connect to the sat nav. We've had this discussion before, and you are talking a load of pish. Of course there is a delay in the signal. Depending on signal quality/strength due to the equipment in use and any obstructions (tall buildings, overhanging trees, cloudy sky etc) this is going to vary, but with modern equipment the delay should be minimal. But all of that is a total moot point when you are discussing constant speed. When travelling at a constant speed it doesn't matter whether the satellite signal delay is 2m/s or 2 minutes (so long as you are measuring the constant speed for more than 2 minutes, of course), because nothing is changing. Any delay in the signal will only be of significance during a change of speed, i.e. if accelerating rapidly and there is a significant signal delay it may show your speed as being 60mph when you have already reached 70mph. As an example, there is a 50mph average speed zone on the A1 near Newcastle, that lasts for several miles and takes approx 15 minutes end to end if travelling at 50mph. I've been through this several times in recent months when travelling twixt London and Edinburgh. I usually set the cruise control so that I am travelling at 49/50mph on the sat nav (in this case a Garmin Nuvi). Since I'm travelling at a constat speed for 15 minutes, and have never suffered a signal issue there, I expect my sat-nav measured speed to be bob on. However, despite not exceeding the posted limit, I still get the flashing warning signs at the road side that tell me to SLOW DOWN. The road signs that display your speed have always been spot on too, compared to my sat-nav speed. If you've not found this to be the case then I would suggest that it's either becuase you weren't travelling at a constant speed when you entered the radar range of the sign (and your sat nav is still adjusting), or it's displaying the speed of another vehicle within range, or that particular sign has been calibrated to give a misleading readout (yes, I'm implying that the powers that be would employ dirty tactics to get us to slow down). On a seperate note (but still on topic, sort of) the speedo calibration is hideous on most modern cars. Everything I've driven in recent years that was fairly modern has over-read, with the worst being a 307 that showed 35mph when I was doing 30mph. All my 205s have been bob on, and my current one is within 0.5mph from 0-70mph, and about +- 1-2mph from 70 to 130. EDIT: Or the other possibility is that Tom Toms are just really s*it Edited December 5, 2010 by GLPoomobile Share this post Link to post Share on other sites
Flozman 4 Posted December 5, 2010 Just got myself some 1.9 wheels, will I need to get anything done to fit them such as the speedo recalibrated? Back on topic... No. Share this post Link to post Share on other sites
Peetypug 5 Posted December 5, 2010 i've got 1.9 wheels on mine and its no different the speedo needle still wobbles like fook! Share this post Link to post Share on other sites
TT205 42 Posted December 5, 2010 (edited) It's not the wheels, it's the tyre size!! Providing the wheels/tyres you had on before were original to the car, use the tyre size calculator on this page http://www.carbibles.com/tyre_bible_pg4.html Enter your original tyre size, followed by your new tyre size and this will tell you the difference (speed wise) of the two eg if you went from a 185 65 14 on a 1.6 (14") rim to a 195 50 15 on a 1.9 (15" rim) then at 70mph your speedo will over read by just over 2mph compared to the original Edited December 5, 2010 by TT205 Share this post Link to post Share on other sites
blessed6383 0 Posted December 5, 2010 thats a handy guide so my 17's are only just running over 1% bigger Share this post Link to post Share on other sites
JRL 14 1 Cars Posted December 5, 2010 i've got 1.9 wheels on mine and its no different the speedo needle still wobbles like fook! I was always under the impression the speedo cable stretches and im sure they do but a around a year ago i had the dial surround off and at the back I pushed a cable in that was slightly loose Im not sure if its just luck or like hitting it with a hammer sort of thing but now the neddle no longer flickers. Share this post Link to post Share on other sites
SurGie 54 Posted December 5, 2010 Thats right, the speed signs are correct yet my tom tom is still 2mph out at least when driving past them. I dont mean disturbing the signal i meant the signal going from car to satellite takes time to regulate, not sure how much though. I have tested it again and again, on motorways and 30mph limits yet its still the same. Im not saying all sat navs are wrong just that they cant be that accurate, or at least mine isn't. To sum it up. To say they are totally accurate without proper testing is the same as saying many cars speedos are inaccurate, there is no real evidence to say either way is there ? Share this post Link to post Share on other sites
GLPoomobile 958 Posted December 5, 2010 So we've established that a} you don't need to do anything about the speedo when fitting 1.9 alloys to a 1.6 b} Tom Toms (or at least Surgie's Tom Tom) are inaccurate Share this post Link to post Share on other sites
SurGie 54 Posted December 5, 2010 the speedo needle still wobbles like fook! I have found that it's the speed cable to be at fault when the speedo wobbles, fit a new one it should work steady. Share this post Link to post Share on other sites
Peetypug 5 Posted December 5, 2010 (edited) was being sarcastic Edited December 5, 2010 by sorrentopete Share this post Link to post Share on other sites
davey205 7 1 Cars Posted December 6, 2010 It's not the wheels, it's the tyre size!! Providing the wheels/tyres you had on before were original to the car, use the tyre size calculator on this page http://www.carbibles.com/tyre_bible_pg4.html Enter your original tyre size, followed by your new tyre size and this will tell you the difference (speed wise) of the two eg if you went from a 185 65 14 on a 1.6 (14") rim to a 195 50 15 on a 1.9 (15" rim) then at 70mph your speedo will over read by just over 2mph compared to the original Thanks for that guide, provided i stay to those sizes a little overread then, no problem ill dust off the talex as a backup. Share this post Link to post Share on other sites
