Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: Hannah Judes Dad on 18 April 2011, 20:06:52

Title: What is the correct size of tyre for 17" wheels ?
Post by: Hannah Judes Dad on 18 April 2011, 20:06:52
As per the header,I'm looking at a set of 17" wheels on egay at the moment that were on a Vectra the present size is 215 50 17.Will these be ok to use as is or will they need new rubber? Thanks in advance folks  :y
Title: Re: What is the correct size of tyre for 17" wheels ?
Post by: Andy B on 18 April 2011, 20:15:25
Quote
As per the header,I'm looking at a set of 17" wheels on egay at the moment that were on a Vectra the present size is 215 50 17.Will these be ok to use as is or will they need new rubber? Thanks in advance folks  :y

235 45 17  ;) ;) No idea of the comparable rolling radius though  :-/
Title: Re: What is the correct size of tyre for 17" wheels ?
Post by: Hannah Judes Dad on 18 April 2011, 20:37:16
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Quote
As per the header,I'm looking at a set of 17" wheels on egay at the moment that were on a Vectra the present size is 215 50 17.Will these be ok to use as is or will they need new rubber? Thanks in advance folks  :y

235 45 17  ;) ;) No idea of the comparable rolling radius though  :-/

Judging by the size difference it will show that my car is going faster than it really is but I wonder by how much ?
I hope someone on here can work it out,I'm too thick  :-[
Title: Re: What is the correct size of tyre for 17" wheels ?
Post by: henryd on 18 April 2011, 20:57:32
The two sizes mentioned have about 0.5km/h difference in them so negligible,sorry it's km/h but that was the site I used :y
Title: Re: What is the correct size of tyre for 17" wheels ?
Post by: Elite Pete on 18 April 2011, 21:23:23
You may have an insurance issue as well so I would let then know you've changed the tyre size ;)
Title: Re: What is the correct size of tyre for 17" wheels ?
Post by: hotel21 on 18 April 2011, 21:35:41
http://www.miata.net/garage/tirecalc.html

 :y
Title: Re: What is the correct size of tyre for 17" wheels ?
Post by: Hannah Judes Dad on 18 April 2011, 21:36:53
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The two sizes mentioned have about 0.5km/h difference in them so negligible,sorry it's km/h but that was the site I used :y

No problem it equates to less than 0.32 mph so it's nothing to worry about  :y
Title: Re: What is the correct size of tyre for 17" wheels ?
Post by: twiglet on 18 April 2011, 22:56:38
What about the offset? I thought Omega's had a different offset to the FWD vxl's. Not sure if this would be an issue though...
Title: Re: What is the correct size of tyre for 17" wheels ?
Post by: Terbs on 19 April 2011, 11:02:41
I bought my Omega with 17" alloys fitted. Are they not the ones it started life with? Had the geometry all checked out at WIM a while back, and nothing was said about the wheels not being 'normal'. My tyres are 235/45/17  :y
As Pete mentions insurance....do I need to contact them. I am sure handbook lists my tyres, will have to dig it out. :(
Title: Re: What is the correct size of tyre for 17" wheels ?
Post by: Andy B on 19 April 2011, 11:05:20
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I bought my Omega with 17" alloys fitted.
your car is a facelift  ;) so were standard.

Quote
Are they not the ones it started life with?  .....
No. His car came with 16" cos it's prefacelift.  :y
Title: Re: What is the correct size of tyre for 17" wheels ?
Post by: Terbs on 19 April 2011, 11:08:56
Thanks Andy :y
Title: Re: What is the correct size of tyre for 17" wheels ?
Post by: hotel21 on 19 April 2011, 11:10:30
Elites generally had alloys as standard however, over several years/owners, may have steels fitted - or vice versa, if it started with steels.

Have a look through the gallery section and see the range of standard alloys.  The ones on mine are factory standard and 235/45-17. 

(http://i83.photobucket.com/albums/j298/hotel21/elite/P1060892.jpg)
Title: Re: What is the correct size of tyre for 17" wheels ?
Post by: duggs on 19 April 2011, 13:29:04
I have 235's on my Elite along with Vectra C wheels. See "Sunny Suffolk Day" in the gallery section.
Title: Re: What is the correct size of tyre for 17" wheels ?
Post by: Malcolm_D on 19 April 2011, 17:41:01
Quote
Elites generally had alloys as standard however, over several years/owners, may have steels fitted - or vice versa, if it started with steels.

Have a look through the gallery section and see the range of standard alloys.  The ones on mine are factory standard and 235/45-17. 

(http://i83.photobucket.com/albums/j298/hotel21/elite/P1060892.jpg)

Totally off thread but is there a guide to include pictures of this size in a forum message?  :-[
Title: Re: What is the correct size of tyre for 17" wheels ?
Post by: Mr Gav on 19 April 2011, 18:02:23
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What about the offset? I thought Omega's had a different offset to the FWD vxl's. Not sure if this would be an issue though...

I think it`s a potential issue, Omegas use a 33mm offset where as the Vectra uses something like a 40mm offset. This means your wheels will be sat 7mm further in than standard.
The wheels on my omega are 7x17 and have a 40mm offset and they just don`t look right, also both front wheel bearings have failed recently and looking through the service history I`ve found that they done in 2007 and I`m convinced that the premature failure on both at the same time is caused by the wheels using the wrong offset.
As for the correct size for a 17" wheel, it depends on the width, a 235 would be too wide for a 7" rim but fine for a 8" rim.
Title: Re: What is the correct size of tyre for 17" wheels ?
Post by: polilara on 19 April 2011, 19:04:48
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Quote
Quote
As per the header,I'm looking at a set of 17" wheels on egay at the moment that were on a Vectra the present size is 215 50 17.Will these be ok to use as is or will they need new rubber? Thanks in advance folks  :y

235 45 17  ;) ;) No idea of the comparable rolling radius though  :-/

Judging by the size difference it will show that my car is going faster than it really is but I wonder by how much ?
I hope someone on here can work it out,I'm too thick  :-[
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Just for info if you have to calculate the circumference without these tyre size calculators:
235/55 16; (16"+2*0.55*235/25.4)*3.1415=82.2"
245/45 17; (17"+2*0.45*245/25.4)*3.1415=80.7"
In this case the 17" wheel rotates slighty faster (about 1.9% faster). Perhaps not a big difference -  according to the owners manual both sizes are OK at least for my Omega.
Title: Re: What is the correct size of tyre for 17" wheels ?
Post by: Hannah Judes Dad on 20 April 2011, 00:16:53
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Quote
I bought my Omega with 17" alloys fitted.
your car is a facelift  ;) so were standard.

Quote
Are they not the ones it started life with?  .....
No. His car came with 16" cos it's prefacelift.  :y

As my car is 1996 it has 15" wheels on at the moment as that is what came fitted at the factory (back in the day)