Title: Tyre size for these rims that people are useing please ??
Post by: clive on October 14, 2004, 08:52:46 AM
Post by: clive on October 14, 2004, 08:52:46 AM
18 x 8.0j Front +30 Offset
18 x 9.0j Rear +35 Offset
18 x 9.0j Rear +35 Offset
Title: Tyre size for these rims that people are useing please ??
Post by: rx7veilside on October 14, 2004, 11:15:48 AM
Post by: rx7veilside on October 14, 2004, 11:15:48 AM
i think my mania vortex are that offset 235/35/18 on front and 265/40/18 rear but slight rub offside rear need to lift the suspension about 5mm on standard ride height will prob be fine
Title: Tyre size for these rims that people are useing please ??
Post by: Phil Bateman on October 14, 2004, 03:27:37 PM
Post by: Phil Bateman on October 14, 2004, 03:27:37 PM
Forgive my intrusion but 265/40/18 are too big and will give a dia of 669 and speedo error. You need 631 dia or as near as possible to keep the speedo correct. 265/35/18 will give 642, that\'s 1/2" smaller on radius and probably will not rub.
Regards
Phil
Regards
Phil
Title: Tyre size for these rims that people are useing please ??
Post by: rx7veilside on October 14, 2004, 04:25:39 PM
Post by: rx7veilside on October 14, 2004, 04:25:39 PM
i prob got it wrong way round prob 235/40/18f and 265/35/18 rear
Title: Question?
Post by: TonyBlair on October 14, 2004, 04:29:08 PM
Post by: TonyBlair on October 14, 2004, 04:29:08 PM
Hi Phil,
I am right in thinking that whenever you change the diameter of your tyres then your speedo will need to be re-configured to reflect the change?
I remember some years my friend told me that they\'d seen 140mph on the speedo in his old and severly battered Calibre 2.0l (non-turbo). I found this hard to believe and attributed it to the fact that he had installed larger wheels. Yet... when I asked another friend about it he told me that changing the wheel size would not affect the speedo, was he right?
Cheers
Jon
I am right in thinking that whenever you change the diameter of your tyres then your speedo will need to be re-configured to reflect the change?
I remember some years my friend told me that they\'d seen 140mph on the speedo in his old and severly battered Calibre 2.0l (non-turbo). I found this hard to believe and attributed it to the fact that he had installed larger wheels. Yet... when I asked another friend about it he told me that changing the wheel size would not affect the speedo, was he right?
Cheers
Jon
Title: Tyre size for these rims that people are useing please ??
Post by: Phil Bateman on October 14, 2004, 04:56:25 PM
Post by: Phil Bateman on October 14, 2004, 04:56:25 PM
If you increase the overall diameter of the wheel/tyres which connect to the speedo drive then the speedo will read low because the wheels rotate slower. So when your speedo says 70 you may be travelling at 75 + depending on how much you have increased the overall diameter.
The bigger the wheel size the lower the profile to keep the same overall diameter, I am not aware of people having speedos changed.
Original Size
225/50/16 = 225x50%x2 + 16"(406) = 631 mm dia
New size
265/30/19 = 265x30%x2 + 19"(483) = 642 mm dia = 1% error OK
Regards
Phil
The bigger the wheel size the lower the profile to keep the same overall diameter, I am not aware of people having speedos changed.
Original Size
225/50/16 = 225x50%x2 + 16"(406) = 631 mm dia
New size
265/30/19 = 265x30%x2 + 19"(483) = 642 mm dia = 1% error OK
Regards
Phil
Title: Tyre size for these rims that people are useing please ??
Post by: TonyBlair on October 14, 2004, 05:02:11 PM
Post by: TonyBlair on October 14, 2004, 05:02:11 PM
Thanks for the technical explanation Phil - much appreciated!
;)
Jon.
;)
Jon.
Title: Tyre size for these rims that people are useing please ??
Post by: scooby_si on October 14, 2004, 06:09:48 PM
Post by: scooby_si on October 14, 2004, 06:09:48 PM
yeah IMO always worth havign a play with a GPS device just to get an idea of how accurate yer speedo is for the purposes of ticket etc avoiding i reckon. Given speedos normally overread by as much as 10% (is legal extremity) then a slightly small circumference increase usually isn\'t too bad my 18\'s are just about on the money im speedo terms now....
Si
Si
Title: Tyre size for these rims that people are useing please ??
Post by: Oliver on October 14, 2004, 06:57:03 PM
Post by: Oliver on October 14, 2004, 06:57:03 PM
Hi Clive, I\'m sure about the correct tire/offset for you but here\'s a nice tire calculator site I used when deciding on diameter
http://www.miata.net/garage/tirecalc.html
regards
Oliver
http://www.miata.net/garage/tirecalc.html
regards
Oliver