TIRES -- upsizing and downsizing for winter and summer seasons

It is well known that using a wider and lower profile tire in the spring, summer and fall will increase your cars handling and traction. Although the contrary is true for winter, a wider tire will actually decrease your traction on snow and ice.



picture courtesy of  tirerack.com

215 is the tread width in mm, 45 is the section height (45% of the width), 17 is the rim diameter
You can change all these parameters as long as the overall diameter stays roughly the same.

As an example the summer size on the car is 215/45/17, I have changed the winter tire size to 195/65/15. Not only will the narrower tire increase the snow and ice traction it will cost almost half the price from $257 for the 215/45/17 to $169 for the 195/65/15 (example Nokian Hakka 7 studded).
That's $88 less per tire, now you have to purchase 15" steel rims for winter so that will decrease your savings to $48 savings per tire. (Although you will save your beautiful 17" mags from any salt damage). On top of this you will save $40 ($20+$20) for installation and balancing per tire for uninstalling and reinstalling the summer tires on your mags every year.
Therefore by downsizing you will have a savings of:
$48-$20(first year winter tire installation&balance)+$40=$68 per tire in the first year plus $40 savings for the installation and balancing in each of the subsequent years.
The most important aspect of downsizing for winter is the better traction that a narrower tire will provide by actually cutting through snow.
In all other seasons a wider lower profile tire will increase the handling on your vehicle dramatically.
Below you will find links to websites that offer free tire size calculators:

from 1010tires.com
http://www.1010tires.com/Tools/Tire-Size-Calculator
from tiresizeconversion.com (scroll down a little)
http://tire-size-conversion.com/tire-size-calculator/
from tacomaworld.com
http://www.tacomaworld.com/forum/tirecalc.php

You have to input your original tire size and the new size you would like to use and it will compare the two sizes for you. Here is another example 175/65/15 up-sizing to 185/55/16,
http://www.tacomaworld.com/forum/tirecalc.php?tires=175-65r15-185-55r16
and the original example,
http://www.tacomaworld.com/forum/tirecalc.php?tires=215-45r17-195-65r15
As well on the bottom of the webpage for tacomaworld it will provide you with alternate tire choices such as:

vs 205/55-16   vs 225/45-17   vs 205/50-17   vs 215/50-17   vs 195/65-15   vs 235/45-17   vs 215/55-17   vs 205/45-17

 

Have fun and stay safe.