tire size
#1
02-07-2006, 04:24 PM
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tire size
ok well i have stock 265/75R16 on my truck and the measured 29" caross the face of the tire
my friend has 285/75R16 and the measured 31"
my uncle has the 295/75R16 on his, and they measure 32"
i always thought that the second number was the width "i.e. 75=12.5", so i thought that 305/70R16 would be 33"x12"on a 16 inch rim
..... so do i got it right or not?
my friend has 285/75R16 and the measured 31"
my uncle has the 295/75R16 on his, and they measure 32"
i always thought that the second number was the width "i.e. 75=12.5", so i thought that 305/70R16 would be 33"x12"on a 16 inch rim
..... so do i got it right or not?
#2
02-07-2006, 04:45 PM
Grand Champion
RE: tire size
Read this, it explains everything you ever wanted to know about tire sizes, and then some. Also, most tire diameters are determined when the tire is manufactured, not when it is installed on your vehicle. So, a tire that is said to have a 33" diameter might actually be more like 31" when it is air-up, and flattened out by the load of the vehicle above it.
http://www.tirerack.com/tires/tirete....jsp?techid=46
http://www.tirerack.com/tires/tirete....jsp?techid=46
#3
02-07-2006, 04:52 PM
RE: tire size
Close, here it is:
The first number you know is the width in mm (265)
the second number is an aspect ratio for how tall the side wall is (75)
In this case 75% of the tread width (works out to 265 * .75 = 198.75)
That is the sidewall height, so multiply it by 2 (397.5)
Everyone likes inches better (397.5 / 25.4 = 15.65")
Add that to the wheel diameter (15.65 + 16 = 31.65)
That's the tire outside diameter when new, it's also assuming the tire is perfectly round, hard to measure with a measuring tape due to loading when on the vehicle.
The first number you know is the width in mm (265)
the second number is an aspect ratio for how tall the side wall is (75)
In this case 75% of the tread width (works out to 265 * .75 = 198.75)
That is the sidewall height, so multiply it by 2 (397.5)
Everyone likes inches better (397.5 / 25.4 = 15.65")
Add that to the wheel diameter (15.65 + 16 = 31.65)
That's the tire outside diameter when new, it's also assuming the tire is perfectly round, hard to measure with a measuring tape due to loading when on the vehicle.
