Tyre data calulator (rolling radius, lettering, volume..)
Guys,
After looking on the net for the radius of tyres i found these websites. On the two websites it explains alot (know your tyres for dummies 
http://www.carbibles.com/tyre_bible.html this website explains all the tyre markings bla bla bla.....
http://www.club80-90syncro.co.uk/Syncro_website/TechnicalPages/TRC%20calculator.htm this website when youput in your tyres sizes gives you rolling radius, tyres air volume ect....
Hope this will help someone
Cheers for eers
I've seen several such tire
I've seen several such tire calculators now. Somehow many of them seem to yield different figures ;-)
The one I especially like is http://www.tacomaworld.com/forum/tirecalc.php?tires=215-65r16-235-60r18
However, in the quest of trying to get my tires legalised in Germany, I learned that the authorities will rely on the standardised dimensions when it comes to things like calculating the percentage difference between standard and tuning tires. These standards are defined, among others, by the European Tire and Rim Technical Organisation, or ETRTO. They publish them in handbooks. These aren't available for free or for download to my knowledge, but some of their member tire manufacturers choose to publish some of the data in pdf handbooks you can download free of charge.
Here is the download link to the English language version of such a manual by Continental tires:
http://www.conti.nl/wp-content/uploads/2014/10/Technical-Databook-car-4x...
Another one by Goodyear, containing a few sizes missing from the Conti volume:
https://www.goodyear.eu/de_de/images/Off%20Road%20Ratgeber_2012_tcm1364-... (I've so far only managed to find this in German and it doesn't give radius info.)
If you are wondering why the radius and diameter values don't add up, have a look at the diagram on page 9 of the Conti handbook.
Since the radius values are for a deflected tire under load, they can theoretically be used to calculate the lift, compared to the standard tire size, while the dynamic outer diameter can be used to calculate how much further up the tire could rise up into the wheel well. That is what I tried to do in a spreadsheet with a selection of sizes which then seemed to be some of the more plausible custom tire sizes for the moderate, street-legal build I was planning. I'll upload that to Google docs shortly.
Another useful tool I came
Another useful tool I came across is a wheel offset calculator on the page of an alloy vendor:
http://www.alufelgenland.de/store/ET-Rechner:_:16.html
Also German, but here's one in English:
http://www.1010tires.com/Tools/Wheel-Offset-Calculator
The definite test however will always be the attempt to mount a wheel and see if it collides with the callipers or anything.
Watch too
Another useful tool I came across is a wheel offset calculator on the page of an alloy vendor:
http://www.alufelgenland.de/store/ET-Rechner:_:16.html
Also German, but here's one in English:
http://www.1010tires.com/Tools/Wheel-Offset-Calculator
The definite test however will always be the attempt to mount a wheel and see if it collides with the callipers or anything.
There's a good vid on this somewhere on you tube too.
Syndicate
Here's another nice one
This is aimed at 4x4 users who want to know how changing to a larger tire will affect the vehicle - it not only gives you the effective diameters - it allows you to compare two different sizes and will tel you the effective change in gearing, and if you have different final drive ratios available, how this impact your desired tire size.