StreetStangs.net  

Go Back   StreetStangs.net > Technical > Chassis, Drivetrain, Suspension, Brakes & Tires

Reply
 
Thread Tools Display Modes
Old 06-28-2008, 05:20 PM   #1
QWKSNKE
3v's are slow
 
QWKSNKE's Avatar
 
Join Date: Dec 2004
Location: Here and There
Posts: 17,152
Calculating tire sizes

Since this formula has been put in numerous posts but questions still pop up from time to time I thought I would throw the formula here.

Ex. tire size. 275/40/17

Breakdown
275 = width in millimeters
40 = aspect ratio of width (40%)
17 = wheel diameter

Note.. 1 inch equals 25.4 millimeters

Obviously to determine width in inches you would just divide 275 by 25.4
275/25.4= 10.83 inches

To determine overall diameter of wheel/tire combo..
40% of 275mm = X
275mm x .4 = 110mm

Note that 110mm is only one sidewall and must be multiplied times 2 since you have 2 sidewalls when looking at the overall diameter of a wheel/tire.
110mm x 2 = 220mm

At this point I convert the sidewalls to inches
220mm / 25.4 = 8.66 inches

Add your wheel size (17" in this example) to 8.66 inches
17 + 8.66 = 25.66

So a 275/40/17 is 10.83 inches wide and 25.66 inches tall.

Disclaimer. This is how formula is suppose to work. Actual size varies by manufacturers. For example Nitto drag radials will be a little narrower and shorter while there 555 street tire will almost be dead on with this formula. Also BFG KDW's seem to follow this as well. I don't know baout other tire brands.
__________________
2009 Porsche Carrera S
2008 ///AMG C63.. Eurocharge Tune. RIP
2019 AMG GLC43..wife's
03 F250 SD.. Edge Evo, AFE Stage 1 CAI
08 GT. JBA axle back, FRPP springs, FRPP swaybars.. daughter's
01 Cobra vert... wife's

I need a new toy
QWKSNKE is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 02:46 AM.


Powered by vBulletin® Version 3.8.2
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.