Calculating tire diameter/height?
Thread Starter
|
Junior User
Joined: Feb 2003
Posts: 69
Likes: 1
From: Missouri
Calculating tire diameter/height?
I used to know this but forgot. How do you calculate tire diameter from the tire sizes.
I'm looking for the difference in tire diameter between my 265/75R16's and the new 275/65R18's.
Thanks Guys.
Joe
I'm looking for the difference in tire diameter between my 265/75R16's and the new 275/65R18's.
Thanks Guys.
Joe
Junior User
Joined: Feb 2008
Posts: 59
Likes: 0
here is a link to a pretty useful calculations site
http://www.4lo.com/calc/gearmetric.htm
16" 32.2
18" 34.2
http://www.4lo.com/calc/gearmetric.htm
16" 32.2
18" 34.2
Tuned
Joined: Dec 2007
Posts: 338
Likes: 25
From: Hooterville, WI
using the 265/75/16 as an example it's the cross section (265) divided by 25.4 times the aspect ratio (.75) times 2 plus the rim diameter (16).
265/25.4=10.43 (this is also your tire width in inches).
Then 10.43*.75=7.82
7.82*2=15.65
15.65+16=31.65.
The stock tire height is 31.65".
265/25.4=10.43 (this is also your tire width in inches).
Then 10.43*.75=7.82
7.82*2=15.65
15.65+16=31.65.
The stock tire height is 31.65".
Thread Starter
|
Junior User
Joined: Feb 2003
Posts: 69
Likes: 1
From: Missouri
Thanks guys. So by those calculations the 265/75r16 is 31.65 and the 275/65r18 is 32.07.
What I'm actually wanting to know is if there will be much of a difference in my final drive ratio if I go with 275/65r18's with 4:10 gears compared to the 265/75r16"s with 3:73 gears that I have now. I thought the taller tires would make up for the lower gear ratio but it looks as if there is not enough difference in tire diameter. 275/65r18 and 4:10's will still be lower geared.
Joe
What I'm actually wanting to know is if there will be much of a difference in my final drive ratio if I go with 275/65r18's with 4:10 gears compared to the 265/75r16"s with 3:73 gears that I have now. I thought the taller tires would make up for the lower gear ratio but it looks as if there is not enough difference in tire diameter. 275/65r18 and 4:10's will still be lower geared.
Joe
Thread Starter
|
Junior User
Joined: Feb 2003
Posts: 69
Likes: 1
From: Missouri
This is exactly what I want. I have the 3:73 now and am perfectly happy with it 90% of the time. There are times when I could use just a little more gear to hold speed in OD. Otherwise I just drop to 4th and let her go. I think the 4:10 with the 18's will do me just right.
Joe
Joe
Thread
Thread Starter
Forum
Replies
Last Post
Jonnys.1991
1987 - 1996 F150 & Larger F-Series Trucks
5
Jan 15, 2015 12:37 PM
mbogosia
1997 - 2006 Expedition & Navigator
24
Jun 12, 2009 03:41 PM
