Questions about tires...

[KL4RUNNA97]

im a nub when it comes to tires...

was wondering if anyone could explain how to read tires sizes like ex: (285/75/16)? like what 285 is? 75? 16? also how to tell what size they convert to like 31's 32's,etc?

 

[RonMAIDEN]

285 would be the width in milimeters and the 75 is the aspect ratio which is 75% of the width equals your sidewall height and the 16 is your rim size.

 

[neliconcept]

285 equals 28.5 cm with a 75% aspect ratio of the width which equals sidewall height

28.5 / 2.54 = 11.220 which is one sidewall height

11.220x.75 = 8.415x2 = 16.83

11.220 was the sidewall height if aspect was 100% so i multiplied it by 75% and then multiplied that number x 2

now 16.83+16 is 32.83

thats the size of a 285/75/16

all tires have a little different config

my new goodyear mtrs coming in will be 33.2 inchs tall.

265/75/16 are 31.9 inches tall.

thats how it works mostly

 

[KL4RUNNA97]

thanks a bunch for the help

a bit confusing but i think i got the main idea

the math kind of threw me off... i dont get where you get 2.54 from?

 

[lee]

http://www.miata.net/garage/tirecalcold.html

there ya go

 

[KL4RUNNA97]

haha thanks LEE but i have that saved in my favorites already...

thanks for the thought though

 

[neliconcept]

sorry

1 inch = 2.54 cm

the conversion factor

 

[KL4RUNNA97]

you said 265/75/16 are 31.9 inches tall?

i got 31.64 inches tall....anyways here is my math and see if i do anything wrong

26.5 / 2.54 = 10.43

10.43 x .75 = 7.82

7.82 x 2 = 15.64

15.64 + 16?(im guessing rim size?) = 31.64

 

[neliconcept]

yeah you are right.. I just guessed on that one

but depends on type of tire as well

my goodyear mtrs are around 31.9 to 32 inches tall.

AT and HT tires are around 31.5 or 31.6

my new goodyear mtr 285/75s will be here tuesday.. those will be 33s or 33.2 or whatever.

almost got the mickey thompson baja belted 34 inch tires

 

[KL4RUNNA97]

DAM DUDE HOW MANY TIRES DO YOU NEED!!!

 

[neliconcept]

im just going bigger..

gonna prob keep my 265s mounted in case i need to downsize for a bit

 

[KL4RUNNA97]

how to calculate tires from 33/12.5r15 to ex305/70R16)?

 

[neliconcept]

yes 33x12.5 is essentially a 305/70/16 tire. 315/75/16 is a 35 inch tire by like 13 inchs wide or some shiz.

reverse the math basically.

or get 15 inch wheels lol.. 15s or 17s can be used that way with bigger diameter.. ive seen 40 inch tires fit on 17 inch wheels..