What's all the tire numbers mean??
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MBWorld Fanatic!
Joined: Jun 2002
Posts: 7,894
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From: Connecticut
2003 CLK55
What's all the tire numbers mean??
I don't really know alot about tires....what do these numbers mean.....for example 225/40 ZR17
just like to know how to read a tire. Thanks
just like to know how to read a tire. Thanks
MBWorld Fanatic!
Joined: Nov 2001
Posts: 6,340
Likes: 22
From: Southern California, USA
2003 CL55 AMG
Re: What's all the tire numbers mean??
Originally posted by Stiggs
I don't really know alot about tires....what do these numbers mean.....for example 225/40 ZR17
just like to know how to read a tire. Thanks
I don't really know alot about tires....what do these numbers mean.....for example 225/40 ZR17
just like to know how to read a tire. Thanks
Curiosity of Tire Rack
The first number is the width of the tire in millimeters, measured from sidewall to sidewall. To convert to inches, divide by 25.4 In the example above, the width is 185mm or 7.28".
The second number is the aspect ratio. This is a ratio of sidewall height to width. In the example above, the tire is 7.28" wide, multiply that by the aspect ratio to find the height of one sidewall. In this case, 185x0.60=111mm or 7.28"x0.60=4.36".
The last number is the diameter of the wheel in inches.
To figure the outside diameter of a tire, take the sidewall height and multiply by 2,(remember that the diameter is made up of 2 sidewalls, the one above the wheel, and the one below the wheel) and add the diameter of the wheel to get your answer.
Example...185/60R14 85H or 185/60HR14
185mm x .60=111mm x 2=222mm + 355.6mm(14")= 577.6mm or 22.74"
The letter(s) at the end are basically the speed rateing of the tire.
Speed Rating - Miles/Hour - Kilometers/Hour - Typical Use
N=87 MPH, 140km/h, Spare Tires
U=124 MPH, 200km/h
P=93 MPH, 150km/h
H=130 MPH, 210km/h, Sport Sedans
Q=99 MPH, 160km/h, Winter, LT Tires
V=149 MPH, 240km/h, Sports Cars
R=106 MPH, 170km/h, LT Tires
Z=149 MPH, 240km/h and over, Sports Cars
S=112 MPH, 180km/h
W=168 MPH, 270km/h, Exotic Sport Cars
T=118 MPH, 190km/h
Y=186 MPH, 300km/h, Exotic Sport Cars
See HERE for more info and illustrations.
TR Moderator & Tire God
Joined: Nov 2001
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From: SouthBend, IN USA
depends on the weather
Almost a Member!
Joined: Nov 2001
Posts: 72
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From: San Diego, CA
The other way to compute the overall diameter without having to convert mm to inches and vice-versa...
example:
185/60-14
Using your calculator...
Enter directly - 185 multiplied by 60, divided by 1270 plus 14, equal.
Note: 1270 is a numerical constant.
The final number should yield 22.74, which is the overall diameter in inches.
example:
185/60-14
Using your calculator...
Enter directly - 185 multiplied by 60, divided by 1270 plus 14, equal.
Note: 1270 is a numerical constant.
The final number should yield 22.74, which is the overall diameter in inches.
Member
Joined: Nov 2001
Posts: 136
Likes: 0
From: Cleveland Ohio
2000 Clk 430
In simplier form...
first number is the width on the tire(metric)
Second is height of the sidewall (40 is 40% of the width, 50 would be 50% of the width and so on)
The third number is the diameter of the tire (how tall in inches)
If your tire converted let's say to 10" wide
and your second number was 40, your side wall would be 4" tall (40% of 10")
Hope this doen't give you a headache.
first number is the width on the tire(metric)
Second is height of the sidewall (40 is 40% of the width, 50 would be 50% of the width and so on)
The third number is the diameter of the tire (how tall in inches)
If your tire converted let's say to 10" wide
and your second number was 40, your side wall would be 4" tall (40% of 10")
Hope this doen't give you a headache.
