165 SR13 tyres

[Tunku]

Does anyone know the modern equivalent? eg. is it 165/80 13?

[aw51 121565]

Tunku said:

Does anyone know the modern equivalent? eg. is it 165/80 13?

Off the top of my head, at the time 165/70 had an 82% profile. An 80% ratio will be marked 165/80SR13

http://www.motuk.co.uk/manual_410.htm says that 80% ratio tyres can be mixed with yer original 82% ratio tyres in any combination...

80% ratio (so 165/80SR13, if that is what is currently available) is pretty near to 82% - and acceptable mixed with the others at MoT .

[garethj]

aw51 121565 said:

Off the top of my head, at the time 165/70 had an 82% profile.

Shirely not?

If it's 165/70 then it's 70% profile. If it's just 165 then it was 82% profile, but that's really going back a few years. My 1977 Alfasud Sprint was on "low profile" 70 section tyres so I reckon anything (other then 4x4s) from the mid 1980s will have had 70 profile or lower as standard.

[j44esd]

As already stated, a 165 SR13 would have been a 165/82 SR13 or full profile - a little digging suggests that this tyre would have an ETRTO max (overall) diameter of 595mm; so staying within the -2%/+1.5% you can go 585mm/605mm and a 175/80 R13 is 605mm - so it's pretty close for a modern day equivalent - depends on the vehicle mind and if it's a nice classic, the original tyres will probably be available from places like:

http://www.longstonetyres.co.uk/

or

http://www.vintagetyres.com/

So may be worth a look. (Depends on how much you value originality)

Hope that helps!

[Randy Winkman]

A couple of people above have got it - if the aspect's not mentioned, it's 82%. Even if a tyre spec says 80%, it actually means 82%. There are no 80% aspect ratio tyres as far as I know.

Anyone know where the 82% idea came from? Perhaps a mathematician can tell us the significance of the number?

[j44esd]

Randy Winkman said:

A couple of people above have got it - if the aspect's not mentioned, it's 82%. Even if a tyre spec says 80%, it actually means 82%. There are no 80% aspect ratio tyres as far as I know.

Anyone know where the 82% idea came from? Perhaps a mathematician can tell us the significance of the number?

Don't know about the significance of the 82%, but there is a difference between an 165/80 R13 and a 165R13. I'm darned if I can remember why though, I shall ask the person I had the conversation with at work tomorrow and come back (They may also know the significance of 82%). I also feel sure that there were 90% aspect tyres, but cannot recall how they are expressed.

I'm pretty sure (99.9%) that a 165SR13 has a different overall diameter than a 165/80 R13 so a 165SR13 cannot be a 165/80R13 in drag. So to speak.

I don't currently have access to the in depth technical literature that I do when in the office, so will double check and report back though

[aw51 121565]

garethj said:

aw51 121565 said:

Off the top of my head, at the time 165/70 had an 82% profile.

Shirely not?

If it's 165/70 then it's 70% profile. If it's just 165 then it was 82% profile, but that's really going back a few years. My 1977 Alfasud Sprint was on "low profile" 70 section tyres so I reckon anything (other then 4x4s) from the mid 1980s will have had 70 profile or lower as standard.

Well spotted .