Can anybody tell me what the original tyre "aspect ratio" was of a standard radial tyre fitted to a 15" 5 bolt wheel please. Want to keep the rolling diameter the  same as original with an 8" wide steel wheel (225 tyre I think). Tried googling this but am confused.   Thanks Paul

A standard 155x15 radial would have an aspect ratio of 80-83 degrees.

http://www.wheel-size.com/size/volkswagen/beetle/1966/

From this it looks like the standard fitment is a 165/80x15 which is what I had too.
Then go to:

http://www.csgnetwork.com/tiresizescalc.html


So you can see that the std tyre size of 165/80x15 has a rolling circumference of 79.78 inches means you can work out the percentage difference in circumference of any tyre you consider for a given rim size. so by choosing a size with a circ as near to the standard 79.78", your mileometer and speedo (if standard) will be right.

This site gives you the recommended sizes for rim width:

http://www.tyresizecalculator.com/tyre-wheel-calculators/tyre-size-for-rim-size-width-calculator

Looks like a 225/60x15 is pretty close or a 235/55x15. I hope that helps.

A standard 155x15 radial would have an aspect ratio of 80-83 degrees.

Thanks David

http://www.wheel-size.com/size/volkswagen/beetle/1966/

From this it looks like the standard fitment is a 165/80x15 which is what I had too.
Then go to:

http://www.csgnetwork.com/tiresizescalc.html Thanks Mark this is all helpfull.  I am planning on an 8" wide steel wheel for the back but a pretty slim wheel and tyre for the front. Ideally would like to retain the original speedo. It is the rolling circumference that I am considering at the moment for the front wheels. IVA will not accept a GPS speedo. IVA requires very specific tolerance with regard to accuracy of the fitted speedo. Also steering geometry has to exhibit an observable degree of "self centering".  ;-)upPaul


So you can see that the std tyre size of 165/80x15 has a rolling circumference of 79.78 inches means you can work out the percentage difference in circumference of any tyre you consider for a given rim size. so by choosing a size with a circ as near to the standard 79.78", your mileometer and speedo (if standard) will be right.

This site gives you the recommended sizes for rim width:

http://www.tyresizecalculator.com/tyre-wheel-calculators/tyre-size-for-rim-size-width-calculator

Looks like a 225/60x15 is pretty close or a 235/55x15. I hope that helps.

http://www.wheel-size.com/size/volkswagen/beetle/1966/

From this it looks like the standard fitment is a 165/80x15 which is what I had too.
Then go to:

http://www.csgnetwork.com/tiresizescalc.html Thanks Mark this is all helpfull.  I am planning on an 8" wide steel wheel for the back but a pretty slim wheel and tyre for the front. Ideally would like to retain the original speedo. It is the rolling circumference that I am considering at the moment for the front wheels. IVA will not accept a GPS speedo. IVA requires very specific tolerance with regard to accuracy of the fitted speedo. Also steering geometry has to exhibit an observable degree of "self centering".  ;-)upPaul


So you can see that the std tyre size of 165/80x15 has a rolling circumference of 79.78 inches means you can work out the percentage difference in circumference of any tyre you consider for a given rim size. so by choosing a size with a circ as near to the standard 79.78", your mileometer and speedo (if standard) will be right.

This site gives you the recommended sizes for rim width:

http://www.tyresizecalculator.com/tyre-wheel-calculators/tyre-size-for-rim-size-width-calculator

Looks like a 225/60x15 is pretty close or a 235/55x15. I hope that helps.

A standard 155x15 radial would have an aspect ratio of 80-83 degrees.

Sorry, that should be percent of course...

A standard 155x15 radial would have an aspect ratio of 80-83 degrees.

Sorry, that should be percent of course...

DAVE..  no apology needed. Realised it would be percentage.