My tire calculations

[87gnblackdemon]

I wanna make sure I have this right before buying. All of my calculations are according to tirerack.coms tech section.

I want to upgrade to either 16 or 17 inch wheels all around. I also want to go with skinny on front ,wide on back, but keep the profile or aspect of the front and back wheels close if not the same.

Heres what I've come up with:
245/45/16 or 17's comes to 4.3 section height ,these would be the rear tires.
215/50/16 or 17 comes to 4.2 section height, front tires.

As close as I could get the two sets.

Those of you who know how to do this conversion, am I correct?

 

[Jimn8or]

Gn's came with 215/65/15's oem
This should help;
http://www.dsm.org/tools/tiresize.htm
Jim

 

[wagon]

OK, got a pencil? Here is how I do them:
Stock Turbo Regal tires: 215/65R15
215 is the width in millimeters
65 is the Aspect Ratio. That is, the sidewall is 65% the width.
R=radial
15 Rim diameter in inches.

Formula>> width/25.4=width in inches (because there are 25.4mm in one inch)
215/25.4=8.46

Width times AR = Sidewall
8.46* 0.65 = 5.5 in

Mulitiply by 2, since you have the top and bottom sidewall to make up the tire height.
5.5*2 = 11

Add the Rim size and you get overall height.
11+15 = 26


Condensed version(s):
Width/25.4=width in inches
Width/25.4*AR=Sidewall
Width/25.4*AR*2+Rimsize= Height

Have fun. It's amazing how many tire shop guys have to break out the books to look them up. If the book doesn't have it, they just tell you they don't know.

Brian

 

[strikeeagle]

It's always best to consult the manufacturer's data for the particular tire or tires in mind, because the sizes given (for example, 215/65R15) are nominal.

Having sold many brands and models of tires before and during my college years, I can ABSOLUTELY ASSURE YOU that if you stood a dozen 215/65R15s of various brands and models next to one another, no two would be the same size...

 

[SinistrV6]

Easy calculator/comparison tool

click here

http://www.1010tires.com/TireSizeCalculator.asp

 

[87gnblackdemon]

Thanks for all your help fella's. The way I did it was almost like Wagon's way.

This is according to Tirerack.com

215/65/15 stock rim
215/ 25.4= 8.5
8.5x.65=5.5 aspect ratio

245/45/16 or 17: 245/25.4=9.6x.45=4.3
215/50/16 or 17: 215/25.4=8.4x.50=4.2

The closest set I could come up with so far.

 

[87gnblackdemon]

Found a set that matches even better.

Front:215/65=5.50
Rear:255/55=5.52

Plus it will probably look better with a clear difference in width from front to back for that skinny to fat look.