What do the tire size numbers mean?
Thread Starter
Member
Joined: Jan 2001
Posts: 149
Likes: 0
From: Nashville, Tn USA #1!
What do the tire size numbers mean?
I thought I knew. A p255/50r16 is a wide-*** tire on a 16" wheel. 255 what? inches? feet? 50r-16 or is it 50-r16. 50 what? R?
$180 each for Goodyear tires this size? That sux!
What's the widest size that will fit a '91 Formula without rubbing the wheel-wells on sharp turns?
Gee, I'm pretty stupid!
$180 each for Goodyear tires this size? That sux!
What's the widest size that will fit a '91 Formula without rubbing the wheel-wells on sharp turns?
Gee, I'm pretty stupid!
Joined: Dec 1999
Posts: 5,964
Likes: 37
From: Hacienda Heights, CA
Car: 90 RS 'Vert, 88 IROC-Z, 88 Firebird
Engine: 305 ci tbi, 305 ci tpi, 350 ci tpi
Transmission: WC-T5, WC-T5, 700R4
Axle/Gears: 3.45, 3.27, 3.27
255 mm = 10 inches wide. 50 is the aspect ratio of the side wall height to width. "r" stands for radial tire.
According to Car Craft's March 2000 issue "Biggest tires for your muscle car": 16": 16 X 8 w/4-1/2" b.s. (back spacing) front, 16 X 8 w/5-1/8" b.s. rear. Use tires with an aspect ratio of 55 or less with a section width of 255. 17": 17 X 9 w/5-1/2" f & r. Use a tire with an aspect ratio of 40 or less with a section width of 255 front & 275 rear. they include recommendations for 15" & 18" for out thirdgen's as well.
According to Car Craft's March 2000 issue "Biggest tires for your muscle car": 16": 16 X 8 w/4-1/2" b.s. (back spacing) front, 16 X 8 w/5-1/8" b.s. rear. Use tires with an aspect ratio of 55 or less with a section width of 255. 17": 17 X 9 w/5-1/2" f & r. Use a tire with an aspect ratio of 40 or less with a section width of 255 front & 275 rear. they include recommendations for 15" & 18" for out thirdgen's as well.
Supreme Member
Joined: Mar 2000
Posts: 13,414
Likes: 6
From: Central NJ, USA
Car: 1986 Firebird
Engine: 2.8 V6
Transmission: 700R4
To get height of that P255/50r16...
Lonsal gave you the width, 255 mm / 25 (cm/mm conversion) = 10.2 inches.
Take that 10.2 inches, multiply by 0.50 percent aspect ratio. 10.2 * 0.50 = 5.1 inch sidewall height.
Multiply the sidewall height by two (bottom and top sidewall), and add 16 (height of rim). (5.1 * 2) + 16 = 26.20 inches tall.
Feel free to ignore that extra 0.20 inches! Half of that reason's because you'll never notice it missing.
The other point is, your actual tire won't be exactly 26.20 inches. Two tires by two different manufacturers can be different heights!
Here's a fun fact for you- a stock tire for a V6 car is a P215/65r15. That's a 26.18 inch tall tire- close to the height of the P255/50r16!
[edit] Oh, and that's why I stopped buying Goodyear tires. The way I like to go through tires, it's not worth it.
Now I buy BFG Radial T/a's.
------------------
-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!
[This message has been edited by TomP (edited March 07, 2001).]
Lonsal gave you the width, 255 mm / 25 (cm/mm conversion) = 10.2 inches.
Take that 10.2 inches, multiply by 0.50 percent aspect ratio. 10.2 * 0.50 = 5.1 inch sidewall height.
Multiply the sidewall height by two (bottom and top sidewall), and add 16 (height of rim). (5.1 * 2) + 16 = 26.20 inches tall.
Feel free to ignore that extra 0.20 inches! Half of that reason's because you'll never notice it missing.
The other point is, your actual tire won't be exactly 26.20 inches. Two tires by two different manufacturers can be different heights!Here's a fun fact for you- a stock tire for a V6 car is a P215/65r15. That's a 26.18 inch tall tire- close to the height of the P255/50r16!
[edit] Oh, and that's why I stopped buying Goodyear tires. The way I like to go through tires, it's not worth it.
Now I buy BFG Radial T/a's.------------------
-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!
[This message has been edited by TomP (edited March 07, 2001).]
Thread
Thread Starter
Forum
Replies
Last Post
toronto formula
Engine/Drivetrain/Suspension Parts for Sale
15
Nov 10, 2015 06:17 AM
knight72
Engine/Drivetrain/Suspension Wanted
0
Aug 10, 2015 09:32 PM
