16" Tyre Size?

[Mitchell]

I've currently got standard dynamique wheels on my car with 185/55/r15 tyres on, which are all different brands etc.

I have bought some 16" Renault OZ f1 alloys, but they have no tyres. My first guess is that for them to have the same rolling radius, I'll need to get something along the lines of 195/45 or 40/r15.

Can someone clear me up with what I need to get on there

Cheers, Mitch

 

[JD]

Not sure about getting the same radius, need someone more in the know, but if it helps I went from 185/55/R15 to 195/45/R16 when I went from standard to sport wheels. Not seen any difference in how much the speedo is out by (usual safety difference of about 3-5mph).

 

[Mitchell]

Cheers for that JD, at least I've now got an idea of what to look for.
They'd probably be able to give me some more information when I take them to get fitted up I presume, unless anyone else on here tells me different!

 

[EllD90]

185/55/15 to 195/45/16 4mm less rolling radius

 

[JD]

There we go, someone who can work it out Sure 4mm won't make a massive difference to you but always worth a check.

One of the first things I changed actually, went from 14 steelies (can't remember the size) to 185/55/15 to the 16s a year later. Never had any issues

 

[Mitchell]

Yeah that will be fine, Cheers for the help
Got the wheels for a bargain so I'm happy about that.

 

[Mesa]

The second number on the tyre is a ratio to it's width (first number) so:

185/55/15 = 55% of 185mm = 101.75mm add the 15" (381mm) TOTAL = 482.75mm
195/45/16 = 45% of 195mm = 87.45mm add the 16" (406.4mm) TOTAL = 493.85mm

Which gives a speedo difference: 0.475% too fast

 

[JD]

Very helpful that, Mesa, cheers.

 

[Mitchell]

Perfect. Now I've just got to wait for the wheels then find some tyres!

 

[EllD90]

I was lazy and used an online source