Understanding tire measurements can be very tricky and complicated, especially when tires are similar in size but described using different measurements. There is the metric measurement and the imperial or standard measurements and these can become confusing very quickly. So what is the main difference between 35×12.5R17 vs 315/70R17 tire?
The 35” tire represents the overall combined width (mm), aspect ratio (%), and wheel diameter (inches) measurement. The 315 tire measurement is a metric value and only represents the tire width which is measured in millimeters.
The two sizes are almost the same, but vary somewhat between tire models and brands. Let’s find out what the exact differences are between the two tires when it comes to size, weight, height, and load ratings.
35×12.5R17 vs 315/70R17 – SIZE/WEIGHT/HEIGHT/LOAD Differences Explained
So let’s start with the 315/70R17 tire. This tire measurement means the tire is measured as follows:
315 – The tire width, measured in millimeters
70 – The tire aspect ratio (side wall) height, measured in percentage
17 – The tires wheel circumference, measured in inches
Let’s see what that looks like in a formula form
Tire Size: 315/70R17 (35”)
- 315 = the metric width of the tire measured in mm
- 70 = the height percentage (Aspect Ratio) of the sidewall
- (315 width x .70 = 220.5mm)
- Divide mm by 25.4 to get inches
- So….. 220.50 x 2 sidewalls = 441mm (divided by 25.4 = 17.36″)
- 17.36″ + 17″ wheel = 34.362″ approximate tire diameter.
As you can see above, the 315 70 17 tire measures 12.4″ wide and 34.362″ tall.
Let’s now see how that differs to a 35/12.5R17
35×12.5R17 vs 315/70R17 – SIZE Differences
So now we know what the 315/70R17 represents, let’s look at how to read and decipher the 35×12.5R17 measurement.
When looking at a 35×12.5R17, the 35” measurement represents the overall tire size which includes the width, aspect ratio and wheel diameter.
The 12.5 represents the section width. The Section width is defined as the measurement between the widest point of the outside sidewall to the widest point of the inner sidewall.
17 represents the wheel diameter, measured in inches.
35×12.5R17 vs 315/70R17 – WEIGHT Differences
These two tire sizes might differ slightly in physical dimensions, however there are factors like load ratings, tire tread pattern, tire molds etc. that makes the difference. The weight differences can vary between 500g to 1.kg or 1.102 to 2.204 pounds.
|Diameter inches (mm)||34.36 (872.8)||35.03 (889.72)||0.67 (16.92) 1.9%|
|Width inches (mm)||12.4 (315)||12.52 (318)||0.12 (3) 1%|
|Circum. inches (mm)||107.95 (2741.98)||110.04 (2795.14)||2.09 (53.16) 1.9%|
|Sidewall Height inches (mm)||8.68 (220.5)||9.01 (228.96)||0.33 (8.46) 3.8%|
|Revolutions per mile (km)||586.93 (364.7)||575.77 (357.76)||-11.16 (-6.94) -1.9%|
35×12.5R17 vs 315/70R17 – HEIGHT Differences
As you can see in the above table, the differences in aspect ratio (sidewall height) is roughly 3.8%.
The table below will show how the aspect ratio affects the accuracy of your speedo readings.
|Speedo Reading||Actual Speed|
|20 mph (32.19 km/h)||20.39 mph (32.81 km/h)|
|25 mph (40.23 km/h)||25.48 mph (41.01 km/h)|
|30 mph (48.28 km/h)||30.58 mph (49.22 km/h)|
|35 mph (56.33 km/h)||35.68 mph (57.42 km/h)|
|40 mph (64.37 km/h)||40.78 mph (65.62 km/h)|
|45 mph (72.42 km/h)||45.87 mph (73.82 km/h)|
|50 mph (80.47 km/h)||50.97 mph (82.03 km/h)|
|55 mph (88.51 km/h)||56.07 mph (90.23 km/h)|
|60 mph (96.56 km/h)||61.16 mph (98.43 km/h)|
|65 mph (104.61 km/h)||66.26 mph (106.64 km/h)|
|70 mph (112.65 km/h)||71.36 mph (114.84 km/h)|
|75 mph (120.7 km/h)||76.45 mph (123.04 km/h)|
|80 mph (128.75 km/h)||81.55 mph (131.24 km/h)|
|85 mph (136.79 km/h)||86.65 mph (139.45 km/h)|
|90 mph (144.84 km/h)||91.74 mph (147.65 km/h)|
|95 mph (152.89 km/h)||96.84 mph (155.85 km/h)|
|100 mph (160.93 km/h)||101.94 mph (164.05 km/h)|
35×12.5R17 vs 315/70R17 – LOAD Differences
The load range is just a complicated way of telling you what the maximum number of pounds the tire can comfortably support. It’s a common misconception that Size and load rating are related however they actually have very little to do with each other. 315/70R17s are also available in C/D/E rages.
As you go up in ratings you get improved load carrying abilities and a beefier tire however due to the stiffer sidewall, offering little flexibility you can sacrifice ride quality and added unsprang weight.
Personally I am a fan of XL for most 4WD ½ ton trucks and SUV applications. Here the application is key i.e. is it your daily driver or is it used as a work truck etc.
SL – Standard load, normal body ply with regular load capacity, P metric like P255/70R17
XL – Extra load, heavier body ply with high load capacity also P metric
C ply(6) rating, heavier body ply with higher load capacity, LT metric like LT285/70R17
E ply(10) rating, heavier body ply with higher load capacity also LT metric
Gas Mileage Difference between 33 and 35” Tires
You can expect 1 to 2 mpg difference when upgrading from 33” to 35“tires. The larger diameter, width and circumference add to the unsprang weight which has a direct effect on fuel economy, performance, gearing and other drivetrain components.
Users who have made the switch have reported a decrease of anything between 1-2mpg when cruising on the highway and 2-4mpg when driving in the city. Of course, the trucks low-down torque and overall performance outputs plays a major factor and figures will vary from vehicle to vehicle.
It’s not uncommon for Jeep Wrangler owners to fit 35” tires, since they have SFA and plenty of options to improve wheel clearance. Of course, re-gearing is key. Once you fit 35s it recommended to go with either the 5.13 or 4.88 gears. Even though frugal gas mileage shouldn’t really be your main concern when driving a 4WD, many JK owners report a drop of between
Difference between 35-Inch and 315 Tires (Metric Vs Mm)
YES, 315 wide tires are the same as 35” tires although 315 is the tread width in millimeters and 35″ is the tire diameter. 315/70/17 is usually the accepted metric equivalent size for standard/imperial 35-inch tires.
In most cases when comparing physical differences most 35″ tires hardly crack the 34″ mark in actual tire size. If you find a tire that has both “315” and “35” measurements take a look at load range/speed rating to determine the best fit for your application.