How to compare tyre diameters.

[INNAWE]

Hi everyone just found a site to compare rolling diameter of different tyre sizes.
I posted a commented contridicting someones calculations so i appologise for that "Commoler". Hence my reason for tracking down something for everyone.
Hope this help everyone.
Cheers

Tire Size Calculator - tire & wheel plus sizing

let me know if the link works.

[Philthy]

There are a few of these calculators around that usually get linked to when tyre sizes are brought up. That is one of the ones I have bookmarked though

[ducker85]

sorry but just ring you local tyre shop (thats what I do), it's alot easier. As some of these work out load ratings, profile and dont always makes sense on the Australian cars eg. Holden on an American web site

[Troy711]

Tire size calculator is better IMO

[ducker85]

Tire size calculator is better IMO

Sorry but i dont agree I dont see how changing your tyre width affects the overall diametre if the rim and profile doesn't change how can the width make the tyre bigger in diametre? as that calculator surguests?

[Troy711]

Maybe if you explained it better I might able to answer, I don't understand..

[hakhawk]

Sorry but i dont agree I dont see how changing your tyre width affects the overall diametre if the rim and profile doesn't change how can the width make the tyre bigger in diametre? as that calculator surguests?

tyre profile is a percentage of the tyre width.

so say, a 205/60r15, the sidewall "profile" height is 60% of 205mm = 123mm

a 225/60r15, sidewall would be 135mm. which gives a 24mm diameter difference.


last time i rang a tyre shop for a price on an odd tyre size, they wanted to know what type of car it was for, loads of help they were...

[ducker85]

tyre profile is a percentage of the tyre width.

so say, a 205/60r15, the sidewall "profile" height is 60% of 205mm = 123mm

a 225/60r15, sidewall would be 135mm. which gives a 24mm diameter difference.


last time i rang a tyre shop for a price on an odd tyre size, they wanted to know what type of car it was for, loads of help they were...

But I know my tyre profile
Im talking overall diametre which is normal about 647mm
this measurment shouldn't change if the tyres get wider
which is where that calculator says; if the tyre gets wider the diametre changes.
but the profile (and rims) stay the same

[hakhawk]

if you go WIDER, and keep the SAME profile, the diaeter WILL get bigger...

if you cant understand it, best leave the tyre choices to the professionals

[INNAWE]

even thou the profile number is still the same with different width tyres dose not mean the actual profile is the same. Like hakhawk said the profile number is a percentage of the acutal width of the tyre. If you have 2 different width tyres with the same profile measure them and you will see.

[ducker85]

[QUOTE=INNAWE;1289269]even thou the profile number is still the same with different width tyres dose not mean the actual profile is the same. Like hakhawk said the profile number is a percentage of the acutal width of the tyre. If you have 2 different width tyres with the same profile measure them and you will see.[/QUOT

Cheers for making an effort to explain it. I get what mean mean it just seems odd to me. Thanks

[INNAWE]

Sorry ducker89 my bad did not mean to offend.
You dont happen to live in the west of Melb do you?
You have personal number plates?

[ducker85]

Sorry ducker89 my bad did not mean to offend.
You dont happen to live in the west of Melb do you?
You have personal number plates?

Nah man South Aus standard SA plates, you havn't offended me man. i seriously mean thanks, what you said makes sense to me