Winter tyres - Smaller/Same/Bigger than originals ?

Satts

I am going to buy a set of winter tyres.

My summer tyres are 165 70 R13 on steel rims.

Is there any benefit(Increased grip in snow, shorter breaking distance etc.) in decreasing/increasing the size of the tyre when I go to buy my winter tyres ? Or should I stick to the original size ?
i.e. Changing 165 to 155 or 175 or changing 70 to 65 or 60 ?

( No posts telling me i don't need winter tyres in Ireland please. I live in an isolated high up area with lots of steep hills, I just want to know if tweaking the size will make any difference. Also not worried about speedometer inaccuracy)

CiniO

Satts wrote: »

I am going to buy a set of winter tyres.

My summer tyres are 165 70 R13 on steel rims.

Is there any benefit(Increased grip in snow, shorter breaking distance etc.) in decreasing/increasing the size of the tyre when I go to buy my winter tyres ? Or should I stick to the original size ?
i.e. Changing 165 to 155 or 175 or changing 70 to 65 or 60 ?

( No posts telling me i don't need winter tyres in Ireland please. I live in an isolated high up area with lots of steep hills, I just want to know if tweaking the size will make any difference. Also not worried about speedometer inaccuracy)

Only one thing which can help on snow or ice is using tyres that are more narrow.
(i.e 155 instead of 165).
But it wouldn't make any really noticable difference.
It's just they provide bigger pressure on the road (less surface and the same force), so on ice they can better stick to it, and on snow they break into it a bit more.

Don't change the diameter of the wheel.
So if you put instead of 165/70 R13 put 155/75 R13 or 145/80 R13
That will keep wheel diameter almost unchanged.
Remember though, that if on snow and ice they will be better, they might be very funny on the dry surface, as car will be swimming on the sides while turning on bends on such high profile tyres.

Satts

CiniO wrote: »

Don't change the diameter of the wheel.
So if you put instead of 165/70 R13 put 155/75 R13 or 145/80 R13
That will keep wheel diameter almost unchanged.

Is this to keep speedometer/odometer accurate ?
Or to keep road clearance the same ?

FREDNISMO

The narrow tyre would be better, but saying that common sense driving in winter conditions counts for a lot, I know a lad who couldnt get off his driveway last winter even if you give him a snowmobile and his driveway was flat.

CiniO

Satts wrote: »

Is this to keep speedometer/odometer accurate ?
Or to keep road clearance the same ?

Both.

Satts

Would reducing the width of the tyre have any effect on breaking ?

Matt Simis

Satts wrote: »

Would reducing the width of the tyre have any effect on breaking ?

Depends on the conditions, can improve or make worse.
Modern Winters are meant to be ok to match width with originals, but narrower is fine too (and the usual approach).