Tire size
Thread Starter
JK Enthusiast
Joined: Nov 2009
Posts: 131
Likes: 0
From: Ladera Ranch, CA
Tire size
Maybe I'm completely dumb but I can't understand tire sizes...
OK you are talking about 33's, 35" or even 37"...
But how does this apply to sizes like 255/75R17...
I know it is all about the height of whole wheel...
OK you are talking about 33's, 35" or even 37"...
But how does this apply to sizes like 255/75R17...
I know it is all about the height of whole wheel...
JK Newbie
Joined: Nov 2008
Posts: 88
Likes: 1
From: Nogales,AZ
Maybe this will help.
Enter each number in the same order as it reads on your tires sidewall. http://www.wallaceracing.com/tire-aspect-calc.php
Ex. 255/75R17= 32.6
Enter each number in the same order as it reads on your tires sidewall. http://www.wallaceracing.com/tire-aspect-calc.php
Ex. 255/75R17= 32.6
Thread Starter
JK Enthusiast
Joined: Nov 2009
Posts: 131
Likes: 0
From: Ladera Ranch, CA
Maybe this will help.
Enter each number in the same order as it reads on your tires sidewall. http://www.wallaceracing.com/tire-aspect-calc.php
Ex. 255/75R17= 32.6
Enter each number in the same order as it reads on your tires sidewall. http://www.wallaceracing.com/tire-aspect-calc.php
Ex. 255/75R17= 32.6
THX
Now we talking...
JK Enthusiast
Joined: Jul 2008
Posts: 400
Likes: 0
From: Stuttgart, Germany
Just a quick overview on tire sizes as background information. There are multiple ways of expressing tire size. Here are the two that we deal with most.
The first is what we call metric sizing. Lets use your example of 255/75R17. That means the width of the tire (tread) is 255 mm. The sidewall (rim to tread) is 75% of the width of the tire, so 191.25 mm. But we can't stay in the metric system too long, so the 17 on the end is the rim in inches. This system is now used for most passenger cars.
The second system is what is often called standard tire sizing. Let's go with 37/12.50R17, since that's what I have. Here, the tire diameter (tread to tread) is 37 inches. The width (tread) is 12 1/2 inches. And it fits a 17 inch rim. I personally like this because I gan estimate how big 37 inches is, and know that that is the hight of the tire.
You can convert the two, you just have to figure out tire height and width, and do some metric to inch conversions, throw in percentages, some long division, maybe some algebra and remember where you left your slide rule in the 4th grade... Or just go online to one of the tire calculators as previously mentioned.
There are some other ways to designate tire size as well, but we see them much less often. My favorite of these is strictly a Japanese convention, very similar to the metric, but they express the height in an actual measurement and not a percentage but in metric units. Its always fun going to a tire shop with a J-spec car still running these tires.
The first is what we call metric sizing. Lets use your example of 255/75R17. That means the width of the tire (tread) is 255 mm. The sidewall (rim to tread) is 75% of the width of the tire, so 191.25 mm. But we can't stay in the metric system too long, so the 17 on the end is the rim in inches. This system is now used for most passenger cars.
The second system is what is often called standard tire sizing. Let's go with 37/12.50R17, since that's what I have. Here, the tire diameter (tread to tread) is 37 inches. The width (tread) is 12 1/2 inches. And it fits a 17 inch rim. I personally like this because I gan estimate how big 37 inches is, and know that that is the hight of the tire.
You can convert the two, you just have to figure out tire height and width, and do some metric to inch conversions, throw in percentages, some long division, maybe some algebra and remember where you left your slide rule in the 4th grade... Or just go online to one of the tire calculators as previously mentioned.
There are some other ways to designate tire size as well, but we see them much less often. My favorite of these is strictly a Japanese convention, very similar to the metric, but they express the height in an actual measurement and not a percentage but in metric units. Its always fun going to a tire shop with a J-spec car still running these tires.
JK Junkie
Joined: Dec 2008
Posts: 2,540
Likes: 0
From: New France
Example: 255/75R17
255 mm divided by 25.4 = 10.03 inches (width of the tire)
255 mm X 75% = 191.25 mm (height of the tire)
17 X 25.4 = 431.8 mm (diameter of the rim)
(191.25mm X 2) + 431.8mm = 814.30 mm (total diameter)
814.30 divided by 25.4 = 32.05 inches (total diameter)
255 mm divided by 25.4 = 10.03 inches (width of the tire)
255 mm X 75% = 191.25 mm (height of the tire)
17 X 25.4 = 431.8 mm (diameter of the rim)
(191.25mm X 2) + 431.8mm = 814.30 mm (total diameter)
814.30 divided by 25.4 = 32.05 inches (total diameter)