Astra G - Changing my steel wheels to alloys

[PenguinWithHair]

Hi there,

I am the owned of a lovely old Astra mk4 or G, 1999 model. It's a boring car I know but I love it. It currently has steel 175/70/14 wheels, I'm not going to do any fast and furious style modifications on it however I am planning on sticking some alloy wheels on it just to smarten it up slightly. I've bought some second hand 205/50/16 alloy wheels and I'd just like to check with you guys if I need to consider anything before fitting them.

When I fit them I'll let my insurance know, they're only standard vauxhall wheels which came off another mk4 astra so hopefully they should fit. I can tell you they have steel inserts where the bolts go, so will I get away with using my current bolts, or will I need new ones?

I have a 175/70/14 steel spare wheel in the boot, will I get away with using that with my alloys for getting me home or to a garage if I have a flat?

Cheers.

 

[Burnerman]

I'll stick my neck out here.....
The new wheels need to be the same diameter as the old ones, or the speedo will be inaccurate.
Wider wheels may foul the wheel arches on full lock or suspension movement.
Different rims may have a different offset which may cause the tyre to foul the suspension struts, and of course they may not clear the brake calipers.
If the alloys have tapered nuts like the steels they should be ok.
A get you home steel rim is fine - if the diameter matches, as above.
Your insurers should be informed.
John

 

[alan333]

According to a tyre size calculator, your new wheels would be 1921mm circumference, against 1887mm on the old ones. This is close enough for a straight swap and will make a negligeable difference to the speedo readings. In fact the 11mm difference in diameter would be about the same as having new tyres instead of worn ones on your old wheels.
All John points above are, as per all his advice, spot on.
To clarify - wheel nuts (and the hole where they go) either have a flat bottom, or a tapered bottom. Tapered holes must go with tapered nuts, and flat must go with flat.

 

[Nozzle]

And the studs need to have the same PCD. EXACTLY the same. Imperial and metric equivalents isn't close enough.

Nozzle

 

[Astra99]

The Astra G used different size wheels depending on model. The most "popular" alloy size was 15", using 195/60x15 or 185/65x15 tyres. Some of the 1.4 models (especially the base model and the Club) did use 14 inch rims. I would therefore suggest that you would be better off obtaining a full set of alloys secondhand (along with the wheel bolts for the alloys) With 195/60x15, the speedo will read just under 2.5% slow, so an indicated 30mph is a true speed of 30.7 and at 70, 71.5
HTH