Space Saver Wheel - Is my paranoia justified?

[wai]

Yes, the coefficient of friction is non-dimensional so it does not matter how wide your tyres are, you get exactly the same amount of grip. Also, in wet weather, you have a higher contact pressure so reducing the possibility of aquaplaning.

On, a narrow tyre will heat up more (but nothing to worry about in normal highway use), and it will wear quicker.

Many years ago, Alf Costanza raced in the Alfasud series and he went for the narrowest tyre permitted because it would heat up quicker in race conditions. He lost no grip at all.

[Diesel_vert]

Anyhow, just one question. The space saver spares in the video were running at 60 PSI. Seems rather high. What's the accepted wisdom for pressures in these tyres?

A tyre's load capacity is mostly determined by air pressure.

T-type temporary tyres are designed to be inflated and operate at 420 kPa (60 psi).

If the volume is small (T-type temporary tyre) and the load is high (passenger vehicle) then the pressure must also be high (420 kPa or 60 psi).

[brad]

I think the recomended pressure for the space saver is on the fuel flap.

I just pump my spare up to 60 anyway - no matter what it is. Saves dissapointment when you go to put it on the car & it's flat.

[midlifecrisis]

I finally put my full sized spare in. Just needed to razor out a bit of plastic.

[Mountainman]

I just couldn't get myself to do that to mine.

[DV52]

I finally put my full sized spare in. Just needed to razor out a bit of plastic.

midlifecrisis: Very impressive! Can you put back the boot floor thingy into the lowest position, or is the full size tire so large that you can only use the upper position?

[midlifecrisis]

Floor is upper level only.

[adhock]

This is a bit delayed, but hey, others may benefit also. Recently decided the time had come to get the full sized spare (thinking of driving outside the metro area, where 225x45/17 tyres may be scarce or expensive) and so rang around. We have space in the wheel well in the wagon - can't comment on hatches. Alloy 17" is $750 odd just for the wheel! Anyway, Wangara VW offered a 15" steel rim with tyre for $150, rolling radius 2 mm different from 17" rim and 225x45/17 tyre apparently. Recycled from bargain Golfs optioned up to alloys from tin rims, they say. Bargain if so. I'll find out how close the size is later this week, but other dealers should be the same if the solution works. Downside: didn't know this when wheeling, dealing and trying to deal for the purchase 6 months ago.

[midlifecrisis]

I bought 4 alloys - most economical way to get my spare. I plan to sell 2 off. I was think $250 each to others who also want a full sized spare with the proper alloy for looks and full performance. Shipping extra. If anyone is interested private mail me.

[brad]

This is a bit delayed, but hey, others may benefit also. Recently decided the time had come to get the full sized spare (thinking of driving outside the metro area, where 225x45/17 tyres may be scarce or expensive) and so rang around. We have space in the wheel well in the wagon - can't comment on hatches. Alloy 17" is $750 odd just for the wheel! Anyway, Wangara VW offered a 15" steel rim with tyre for $150, rolling radius 2 mm different from 17" rim and 225x45/17 tyre apparently. Recycled from bargain Golfs optioned up to alloys from tin rims, they say. Bargain if so. I'll find out how close the size is later this week, but other dealers should be the same if the solution works. Downside: didn't know this when wheeling, dealing and trying to deal for the purchase 6 months ago.

The 15" will still be regarded as a "temporary spare" and you'll be limited to 80kph. The tyre size will most likely be 195/60r15.

You're better off sourcing something (a whole set maybe) from ebay, gumtree or an AU based forum. It doesn't matter if the style of wheel doesn't match - it's the diameter, width & offset that matters. Just put a 2nd hand tyre on it.

225/45r17 is a really common size these days. 235/45r17 even more so (something to think about when replacement time comes)