quick question: matching tire height
05-20-2006, 12:38 PM
#3
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Installed height I Just measured my tire height. I have Nitto 555 275/35/18 in front with a height of 24 3/4 Rear Nitto 555 II extremes 305/35/18 height of 26 inches installed..
EDIT: i just re-read the original post
EDIT: i just re-read the original post
05-21-2006, 07:56 AM
#5
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To easily convert any tire size:
First off, they are obviously in the metric system
275 = Tread Width in millimeters (Section Width will be slightly greater)
35 = Aspect Ratio of Sidewall Height to Tread Width (this value is in percentage)
18 = Wheel Dia in inches (at least this is still in standard units
)
To find the tire OD (which is what you are mainly looking to match)
#1 Convert Tread Width to centimeters (divide by 10) = 27.5 cm
#2 Convert Tread Width to inches (divide by 2.54) = 10.83 in
#3 Find Sidewall Height (multiply 10.83 by .35) = 3.79 inches
#4 Find Overall Tire Dia (multiply Sidewall Ht. by 2 and add Wheel Dia) = 25.58 in.
This is your existing front tire diameter.
Doing the math for each of the other sizes you mentioned:
295/35/18
#1 29.5 cm
#2 11.61 in
#3 4.06 in
#4 (4.06 x 2) + 18 = 26.13in
295/30/18
#1 29.5 cm
#2 11.61 in
#3 3.48 in
#4 (3.48 x 2) +18 = 24.97in
As you can see, replacement tire #1 is .55in bigger in dia. than fronts and replacement tire #2 is .61in smaller than fronts.
Usually one needs to know tire sizes because they are increasing wheel dia from the stock size and want to keep the same overall tire dia. In that case it is entirely possible to choose a tire size that will very closely match your overall dia's.
However, in your case, you are keeping the same wheel dia. and apparently are simply looking for more meat (wider) tires on the rear. You will never find a tire that will yield the same OA dia. as the original, nor get as close to OA dia. of the original as you would if you were also changing the wheel dia. So basically what I am saying is that if you want wider rear tires AND want to match the front tire diameter closely - you will have to go to a 19" wheel in the rear with the corresponding correct tire size.
I realize you can go on the tire site and they will tell you the tire size needed for each level of upgrade - but thought you might want to know the underlying calculations on how to get to the answer. It's always alot easier to understand what you're talking about if you understand the concept...
-Jay-
First off, they are obviously in the metric system
275 = Tread Width in millimeters (Section Width will be slightly greater)
35 = Aspect Ratio of Sidewall Height to Tread Width (this value is in percentage)
18 = Wheel Dia in inches (at least this is still in standard units
)To find the tire OD (which is what you are mainly looking to match)
#1 Convert Tread Width to centimeters (divide by 10) = 27.5 cm
#2 Convert Tread Width to inches (divide by 2.54) = 10.83 in
#3 Find Sidewall Height (multiply 10.83 by .35) = 3.79 inches
#4 Find Overall Tire Dia (multiply Sidewall Ht. by 2 and add Wheel Dia) = 25.58 in.
This is your existing front tire diameter.
Doing the math for each of the other sizes you mentioned:
295/35/18
#1 29.5 cm
#2 11.61 in
#3 4.06 in
#4 (4.06 x 2) + 18 = 26.13in
295/30/18
#1 29.5 cm
#2 11.61 in
#3 3.48 in
#4 (3.48 x 2) +18 = 24.97in
As you can see, replacement tire #1 is .55in bigger in dia. than fronts and replacement tire #2 is .61in smaller than fronts.
Usually one needs to know tire sizes because they are increasing wheel dia from the stock size and want to keep the same overall tire dia. In that case it is entirely possible to choose a tire size that will very closely match your overall dia's.
However, in your case, you are keeping the same wheel dia. and apparently are simply looking for more meat (wider) tires on the rear. You will never find a tire that will yield the same OA dia. as the original, nor get as close to OA dia. of the original as you would if you were also changing the wheel dia. So basically what I am saying is that if you want wider rear tires AND want to match the front tire diameter closely - you will have to go to a 19" wheel in the rear with the corresponding correct tire size.
I realize you can go on the tire site and they will tell you the tire size needed for each level of upgrade - but thought you might want to know the underlying calculations on how to get to the answer. It's always alot easier to understand what you're talking about if you understand the concept...
-Jay-