bugster70 Legacy Donating Member 1,326 Member For: 21y 4m 25d Location: Canberra Posted 07/11/08 05:05 AM Posted 07/11/08 05:05 AM Tyre calculatorTry this little gem Have I missed something here, or maybe I'm oversimplifying things, but I thought that as long as you kept your rolling diameter the same, your speedo should (technically) not be out at all? As a very rough guide, that means 45 series profile tyres in 17", 40 in 18", 35 in 19" and 30 in 20" - although of course the width of the tyre will play a role too.
trevs Member 781 Member For: 19y 5m 7d Gender: Male Location: balmain Posted 01/01/09 05:30 AM Posted 01/01/09 05:30 AM how does the width have anything to do with it
Xrfranjo Member 350 Member For: 19y 1m 5d Gender: Male Location: Bonnyrigg Heights, NSW Posted 01/01/09 06:42 AM Posted 01/01/09 06:42 AM Try this guy , he is in kings park and the business is called MIS intruments the number is 9621 8190 Ron McMullen... he is Jeffs brother the 60 minutes reporter... he is fantatsic....
Adam Here since the start... Legacy Donating Member 10,282 Member For: 23y 5m 2d Gender: Male Location: Victoria Posted 01/01/09 11:34 PM Posted 01/01/09 11:34 PM Or you can just get Ford to do it. Simple change.My old BA was 4-5km/h under with stock 17's.My current BF MkII is spot on with stock 18's.
INFLYT Legacy Donating Member 784 Member For: 20y 2m 18d Gender: Male Location: N.S.W, Sydney Posted 02/01/09 12:39 AM Posted 02/01/09 12:39 AM Just gotta watch out for those speed camera's...I remember my mate got snapped while cruising my car a couple of year's back. He swore he was sticking to the limit there, but we realised later that the jump from 17's to 22's threw the speedo off about 10 kilometre's over.
wados Member 617 Member For: 21y 11m 11d Gender: Male Location: brisbane Posted 02/01/09 06:46 AM Posted 02/01/09 06:46 AM Tyre calculatorHere try this website, it will tell you all you need to know. Lets say if you went from stock 17's and the speedo was spot on 100 then with 20's on a 30 profile should show 97kmh roughly
jsmith Legacy Donating Member 712 Member For: 18y 11m 4d Gender: Male Location: Blacktown Posted 02/01/09 07:00 AM Posted 02/01/09 07:00 AM how does the width have anything to do with it the tyre profile is related to the width of the tyre, therefore a 235/40 series tyre will have a higher sidewall than a 215/40 tyreBased on that, depending on what size and profile tyres 03XR6T went from and to it would change the speedo more or less than someone else.and back on topic, my car is 9k's out at 110kph (showing 101 @ 110 on speedo). this is with the std 17's and standard tyre sizes.
INASNT Member 361 Member For: 20y 1m 7d Gender: Male Location: Melbourne Posted 05/01/09 10:07 AM Posted 05/01/09 10:07 AM Mine is off by 5 km/hr also going from 18's to 20's.Is there anywhere in SE suburbs of Mel that can recalibrate for a good price?
SIKXE8 Member 100 Member For: 18y 1m 10d Gender: Male Location: S.E Melb Posted 06/01/09 02:05 PM Posted 06/01/09 02:05 PM 20's will vary on how far out the speedo is dependant on the size of the tyremine was out about 9k's at 100K/ph but I got 245x35 on the rearI think from memory a 225x30 tyre will have same rolling diameter or very close to as the factory wheel so it wont be out much
SIKXE8 Member 100 Member For: 18y 1m 10d Gender: Male Location: S.E Melb Posted 06/01/09 02:06 PM Posted 06/01/09 02:06 PM I think an autoelec will be able to calibrate the speedo not to sure thou
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