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ProtoTipo
17-12-2011, 17:59
Can someone remind me:

For road tyres (rather than the 215 TBs) is it normally 205/50 x 15.
Or some other size? It's the aspect ratio I can't remember.
'Don't like the rolling diameter too small.

Guy Mayers
17-12-2011, 18:05
Yup - I've had 205*50*15 on the front and 225*50*15 on the back when the car was a Stradale but now it's Gp4 I went to 345*35*15 and 225*50*15s

Guy

turbonutter
17-12-2011, 18:13
I can agree with Guy on that one - I had 205-50-15's front & 225-50-15 on the rear when I had my last car..

ProtoTipo
17-12-2011, 18:40
Thanks chaps.

Any more votes for 205 50 ?

I don't know what the 215 TBs are for side wall ratio?, but that's the kind of side wall height/rolling diameter I prefer.

turbonutter
17-12-2011, 19:48
205-50-15 is aprox 586mm diameter.

turbonutter
18-12-2011, 09:55
Just found this spreadsheet that I used when looking at what tyres to fit to my car.
1079

ProtoTipo
18-12-2011, 10:50
Thanks Neil.

So a
205-50-15 is 586mm
215 TB15 is 612mm

I've also got (for 205)
55 ratio at 606mm and
60 ratio at 627mm

So maybe 205-55-15 would still be smaller diameter than a TB Michelin?

turbonutter
18-12-2011, 11:42
I get ~607mm for the 205-55-15 which is more or less the same as the tyres you are replacing.. you wount notice 5mm difference ( its less than the diameter change due to tread wear.
Also as you can see from my spreadsheet the actual tyre sizes do not always exactly match the theoretical diameters either.

StruanR
18-12-2011, 13:25
Michelin Racing Size Designation


Road legal sizes


Rolling Circumference


Recommended Rims




16/53-13


175/60R13 72V


1640 mm


5 to 6 inches




20/53-13


225/45R13 77V


1635 mm


7 to 8,5 inches




15/60-15


170/65R15 77V


1847 mm


5 to 6 inches




18/60-15


215/55R15 79V


1885 mm


6 to 7.5 inches




23/62-15


270/45R15 86V


1923 mm


8.5 to 10.5 inches




26/61-15


295/40R15 87V


1891 mm


10 to 11.5 inches




29/61-15


335/35R15 93V


1903 mm


11 to 13 inches




Michelin TB15 sizing..

ChrisCar6
20-12-2011, 00:59
205 / 50 x 15" on my front

ProtoTipo
20-12-2011, 10:52
205 / 50 x 15" on my front

Thanks Chris.