Running car on 2 different wheel sizes

Flight3287462

looks OK to me, difference would appear to be within a new tyre and one down to the minimum tread.  Whether plod would agree is a different matter.

Wonka_2

B0bbyEwing said:

6 posts in & we're still not sure whether it's fine or not. 

Though granted, I see you wouldn't do it Krakkers so thanks. 

At least I know there could be issues with insurance & such. 

Oh well, I'll see how it goes in a bit. 

Legal - will be OK assuming it's compliant with car and doesn't foul brakes etc

What it's likely to do is make you a sitting duck for a police pull - so make sure everything else is in order

B0bbyEwing

Marlot - maybe I used the spacesaver term wrong then. I thought that's what it was but yes it says emergency use only. Either way it's not on the car. 

Wonka_2 - I'll take my chances. Times of day I'm travelling & the lack of lighting as well as the fact the police can't really be bothered when you report someone for having no MOT & even after you spoon feed them evidence they still grumble about doing anything about it.... I fancy I won't get pulled any time soon & certainly not by Friday. 

And if I do then it is what it is. 

Ditzy_Mitzy

The issue, as it stands, is that you will have tyres of mismatched width and side profile on the same axle.  There's nothing wrong, inherently, with a 205/55/16 tyre, but it won't provide quite as much grip as the 225/40/18 on the other side.  The 16" tyre also has a higher sidewall than the 18" one, so will be more prone to deforming in both planes (up and down and side to side) - it will ride slightly better, as a consequence, but the lack of stiffness will result in fractionally less grip through the corners.  Practically speaking, you won't be able to carry as much speed as usual round bends when the rogue tyre is the one doing the work, i.e. bearing the weight of the car.  Do you drive fast?  A gentle driver probably wouldn't notice that much difference; a quick one will need to be mindful and slow down to compensate.  

Out of interest, which axle is the rogue tyre going on and which axle is driven?  

Lots of cars, especially those run on the cheap, will be in a generally similar situation on the basis of having a mixture of makes and types of tyres (not sizes) on the various axles.  Some drivers will have four completely different tyres fitted thus, with each having slightly different tread patterns and rubber composition, will have cars that generate differing amounts of grip at each corner.  I'm not saying that I've done similar myself when younger, but I do know that it can lead to unpredictable handling in both wet and dry.  Fitting four identical tyres was a revelation.  

As always, be careful... 

diystarter7

Hi

I'm confused. Is the spare OE?

All space saver tryres come with a warning as emergency use only and very limited in speed.

Thanks