boost26 Member 51 Member For: 17y 6m 29d Gender: Male Location: Melbourne Posted 12/03/12 09:32 AM Share Posted 12/03/12 09:32 AM I think your dealer is talking crap to you.I went from 245/35/19 to 245/40/19 which is a 5 % change in rolling diameter.Took it in to my dealer and asked them to correct the speedo for larger rolling diameter.They did it no problems and said its good that I got it reflashed to suit larger diameter cause it effects transmission shift points etc..Checking on GPS it was only 1 km/h out at 100 whereas before it was 2k out.They have various options depending on tyre size, rim size has nothing to do with it.Only problem now is since I had it tuned with Xcal3 its back to original settings so my speedo is out again. Link to comment Share on other sites More sharing options...
bionicxr6t05 Bronze Donating Members 2,216 Member For: 13y 4m 4d Gender: Male Posted 12/03/12 10:00 AM Share Posted 12/03/12 10:00 AM No they are correct, using ids you can only set it to manufacturers available sizes we tried setting up an fg ute with 22s on it the other week, no luck Link to comment Share on other sites More sharing options...
boost26 Member 51 Member For: 17y 6m 29d Gender: Male Location: Melbourne Posted 12/03/12 11:31 AM Share Posted 12/03/12 11:31 AM Rim size has nothing to do with it. Its all about the tyre diameter.Unless the diameter is hugely out which would make it unroadworthy they have about a dozen options they can set your speedo to. Link to comment Share on other sites More sharing options...
discostig Manual mode ________________________ All day, erryday Donating Members 13,798 Member For: 17y 6d Gender: Male Location: Probably above atmospheric pressure Posted 12/03/12 12:46 PM Share Posted 12/03/12 12:46 PM Ah wasn't thinking of the big picture with the tyre profile changes, that makes sense. Still, if someone wants to find a PDF from a .gov.au that would settle things. Me, I'm going to go play a game. Link to comment Share on other sites More sharing options...
arronm Dropping a turd Gold Donating Members 9,520 Member For: 17y 1m 4d Gender: Male Location: Perth Posted 12/03/12 02:04 PM Share Posted 12/03/12 02:04 PM Three of our fords (BA BF) read higher than you are actually traveling. Reads 100 but you are traveling 96. Which is good to help not speed. Link to comment Share on other sites More sharing options...
bionicxr6t05 Bronze Donating Members 2,216 Member For: 13y 4m 4d Gender: Male Posted 12/03/12 09:12 PM Share Posted 12/03/12 09:12 PM And using ids you type in the tyre size and it calculates rolling diameter right in front of you, if its out of its range it wont program Link to comment Share on other sites More sharing options...
MexicanBatman G666E Turbo!!! Member 1,008 Member For: 14y 10m 15d Gender: Male Posted 12/03/12 11:28 PM Share Posted 12/03/12 11:28 PM I did a few thousand km on 22's that were massively larger than factory wheelsCar operated fine, speedo was out by miles but when you worked out that this was that speed it was fine. I believe 92km/h indicated was 100km/h actual but I forget now... Link to comment Share on other sites More sharing options...
Worm A much better forum Silver Donating Members 3,808 Member For: 16y 4m 8d Gender: Male Location: Victoria Posted 14/03/12 09:11 PM Share Posted 14/03/12 09:11 PM My 275/30/20 are bigger than standard... But the speedo is perfect! Link to comment Share on other sites More sharing options...
Pazzo Donating Members 11,132 Member For: 14y 1m 9d Gender: Male Posted 14/03/12 09:19 PM Share Posted 14/03/12 09:19 PM What gets me is that a lot of dealers now sell aftermarket wheels as option, like David Nutter Ford in Berwick. So you buying 20s is no good, but them selling 20s is ok? When orded my FG MK2, Courtney Patterson where trying to sell me Roh Prowlers in 20s. No thanks. Link to comment Share on other sites More sharing options...
discostig Manual mode ________________________ All day, erryday Donating Members 13,798 Member For: 17y 6d Gender: Male Location: Probably above atmospheric pressure Posted 15/03/12 04:50 AM Share Posted 15/03/12 04:50 AM Factory rims? Link to comment Share on other sites More sharing options...
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