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Discussion Starter · #1 · (Edited)
Hi All,

I am trying to determine the correct tyre size for my Astra H SRI alloys and was hoping someone might be able to help... having scoured the internet and this forum, I still haven't come up with a conclusive answer!

Alloys are standard fitmement Vauxhall 17" 5-Spoke and my car is a 2004 (54 plate) 1.8 SRI (125 Non VVT).

My original owners manual only lists 215/45/17 and this is indeed what is currently fitted to the car.

However, having read on this forum and elsewhere, it seems this was changed at some point to 225/45/17 being the ideal size for these alloys.

I'm sure you can fit either, but does anyone have any official information about this to clarify, why and when was this introduced?

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It was 225/45’s on my Sri and it’s an 07 plate, the 17s on the van have 215/45’s, can fit either or tho


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Discussion Starter · #4 ·
This is exactly the point I am trying to investigate... both sizes are viable. As I mentioned above, my owners manual only states 215/45/17, so why is 225/45/17 correct? It must have been changed or introduced after a certain production date and for what reason?
 

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The only importance is the 225 are a slightly more expensive tyre, but you need to change them in axles (pair) at a time to stop the abs throwing a wobbler


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Discussion Starter · #7 ·
My manual also states 225 45 17 🤷‍♂️, is it realy that important?
What engine do you have... I was wondering if this was introduced with the later 1.8 VVT, perhaps being a slightly heavier vehicle than the 1.8 non VVT? It's importance can only be determined if we know the reason behind it. Vauxhall wouldn't just change the tyre size for the sake of it, there much be a technical/design/economical reason it was introduced.

The only importance is the 225 are a slightly more expensive tyre
I am finding that the 225 tyres are actually pricing cheaper than 215 at the moment and there are more options being a more common tyre size.
 

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The reason is probably economic, like you say, the 225 seem to be cheaper an fit a lot of other cars, my Sri is a 1.9, the van is a 1.7, the wheels on it came off a 1.9 van which had 215’s on it from new


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Discussion Starter · #10 ·
Ok, can you have a look in your Owners Manuals and see if there are any tyre pressures listed for the Z18XE on 225/45/17 ?
 

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Discussion Starter · #11 ·
Just to add... I spoke to Vauxhall today and they confirmed the only tyre size listed for my vehicle on their database is 215/45/17. No doubt the larger size will fit and no one would notice, however it might invalidate the insurance unless declared. I do think this is something to do with my car being an earlier 2004 model with Z18XE engine, so perhaps the 225/45/17 is only an official size for later cars with Z18XER or other engines.
 
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