Quote:
Originally Posted by Erik219
225/45/17 has equal height as a 205/50/17 .... (1.25 mm diff)
the height indication is in % of the tire width! so to calculate the heights:
**225x45/100 = 101.25 mm height
**205x50/100 = 102.50 mm height
I don't think this 1.25mm will make the difference...
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No NO! I am not saying the size will make any difference in speedo readings. The 225's are just fine for a overall tire size to the 205's or OE summer tires. But what I was trying to say was....
For a winter tire you
WANT skinny and tall sidewall tires. The reason is you want the MOST PSI/Bar pressing down on that small contact patch - in order to get the most traction in snow and ice.
When you go with wider tires and shorter side walls - you are spreading out the pressure more and that is
bad for low traction conditions. The short sidewall is bad bc it will not flex as much and the tire will break traction when corning hard. So the best tire will always be the tallest and narrow tires you can mount. That is why I went with BMW suggestion of 7jx17's with 205/50HR17s.
Also... you don't want a really high speed rating either. No ZRs or even WRs... bc an HR tires will suffice in winter months. The higher speed rattings will come will stiffer sidewalls... also bad for snow tire performance.
hope this helps explian things better.
bye,
David