Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: Glynn on 11 January 2009, 23:19:10

Title: tyre size
Post by: Glynn on 11 January 2009, 23:19:10

just bought a set of 18's from Hotel21 and I'm wondering what profile tyre I need  :-/  some tyre sites tell me 40 , but others say 45 ...any input would be appreciated

it's currently running on 225/55/16's


cheers guys

Title: Re: tyre size
Post by: shanjon on 11 January 2009, 23:22:03

i ran my omega on 235/40/18 s with no noticeable difference 5to speedo , i believe that 45 profiles are best suited to 17 inch alloys

Title: Re: tyre size
Post by: unlucky alf on 12 January 2009, 11:03:54

i believe the profile size should be 35`s for 18" wheels, for every 1 inch up on rim size take 10 off the tyre profile size as a rule, but as shanjon says 40`s will only make a marginal difference on speedo accuracy so should get away with it. :y

Title: Re: tyre size
Post by: hotel21 on 12 January 2009, 11:21:12

225/55-16 gives a tyre circumference of 2054.29 mm.

245/40-18 gives a tyre circumference of 2052.09 mm which is a difference of -2.2 mm or -0.11%.

This means that if your speedo was reading an accurate true speed at 70 on the 225/16's then on the 245/18's your actual speed would be 69.92mph.

Very worthwhile site and a good calculator on page 2.... :y

http://www.carbibles.com/tire_bible_pg2.html

Title: Re: tyre size
Post by: markey mark on 12 January 2009, 12:17:45

225/40 will be your cheapest option  :y