Spare wheel - should it be the same style?

harveybobbles

andygb wrote: »

That does not sound very safe to me, as the rolling radius is 4cm different, and the golden rule is never to put different sized wheels on the same axle, which in this case would be unavoidable as the spare is different to all the others - not good.:(

Eh?

It's only different by 2%

MX5huggy

Lum wrote: »

Might be cheaper to find an Octavia in a scrap yard and buy a wheel, with tyre, from them. That way you get a fullsize spare and a matching alloy design.

I think you miss the point, the full sized spare is a optional extra when buying a new Octavia. It was £55, after 17000 miles my front tyres were down to 2.5mm so I purchased 1 Bridgstone tyre for £78 swapped the new tyre off the spare on to the front and put one of the worn tyres on the spare.

If I did what you suggested I would have spent £20 to £30 at the scrappy and then had to buy 2 £78 tyres at 17000 miles, because I am not going to use some second hand tyre with unknown history as a main tyre.

Lum

Yes, I know, it's crap. On some cars they charge a lot more than £55, or simply don't offer a full size spare at all, even if the wheel well can hold one.

The reason is apparently because, by making it optional, the lower non-spare-equipped weight of the car is used when doing the MPG tests.

MX5huggy

Indeed I had one dealer saying that if I added a spare, the car would have a diffrent CO2 rating, like if a add a tow bar and electric heated leather seats I said. Total cow byproduct.

photome

harveybobbles wrote: »

Eh?

It's only different by 2%

I think they are 3.5cm difference, whatever the correct difference the fact remains that they are different

forgotmyname

185x55x15 = 585mm diameter

185x64x14 = 596mm diameter

1.88% or 11mm.

The difference between a just legal tyre and a new one will be greater than that. So acceptable.

andygb

forgotmyname wrote: »

185x55x15 = 585mm diameter

185x64x14 = 596mm diameter

1.88% or 11mm.

The difference between a just legal tyre and a new one will be greater than that. So acceptable.

If you think that having a new tyre and one at the legal limit on the same axle is safe, then I really do not think much of what you consider is "acceptable".
In the event of an emergency stop, such a vehicle would be all over the road, and even driving at motorway speeds, 11mm difference would require a constant pressure on the steering wheel to keep the vehicle in a straight line.