Different sized wheels on same axle

[rad000]

say i had a set of 16" wheels and one tyre blew, meaning i had to replace it with a spare, and the spare wheel is 15", what effect would this have? i'm asking this because i'm thinking of buying 16" wheels and i have 15s at the moment, so there would be a bit of a gap between getting them and getting a 16" spare. my guess is it would be dangerous, but how dangerous?

[DJKOR]

When you get new wheels, you are meant to aim to get a tire that makes the overall wheel and tire diameter be as close to the factory wheels/tires as possible. So long as you adhere to that general rule, you will be fine to keep your previous wheels as a spare. You should try to only use it as such though and aim to get the (new) wheel back on ASAP, but it's not going to be a massive issue if you continue using the stock wheel for any reason.

With a larger variation in overall diameter, you will notice that your car may handle a little differently (eg. pull towards one side more), and may respond a little differently when braking. If the variation isn't overly massive, it's not exactly what I would define as dangerous, but I wouldn't say it's exactly safe either. In a condition like this, I would definitely only use a stock wheel as a spare for the least amount of distance you require it for.

[Ronnyboy]

When you get new wheels, you are meant to aim to get a tire that makes the overall wheel and tire diametre be as close to the factory wheels/tires as possible. .

Thats correct...

As long as the overall Diameter is the same size as your current tyres you should be fine :)

[private number]

I'm running a 19 inch wheel and one time my tyre went flat so I chucked on my stock spare. Only issue i had was slight vibrations. Nothing scary.

[rad000]

oh wow thanks heaps! i was thinking everyone would say it's a stupid thing to do but now i'm glad i asked! thanks guys

[Hiro]

It should only be used as a short term solution though - as soon as you can get the flat etc fixed then get it back on. The biggest issue when using odd pairings of wheels is if they are used on a driven axle, in which case they will be permanently loading up the differential which can affect its life significantly.