What is total tire height and how is it calculated?

Total tire height: also called overall diameter: is the full outside-to-outside measurement of a mounted tire. It equals the wheel (rim) diameter plus twice the sidewall height. Sidewall height is derived from the P-metric code: Sidewall (in) = (Width mm × Aspect Ratio ÷ 100) ÷ 25.4. For a 265/70R17 tire: sidewall = (265 × 0.70) ÷ 25.4 = 7.30 in, giving a total height of 17 + 2 × 7.30 = 31.61 in. This is why 'tire height' and 'tire diameter' refer to the same measurement: the outer diameter of the mounted tire.

What is the ±3% guideline for tire height changes?

Continental advises keeping the rolling circumference within 3% of the original. For a stock 265/70R17 (31.61 in), that window is 30.66 to 32.56 in (calculated). It is not a vehicle maker specification: most owner's manuals publish no percentage and ask for the same size and type on all four wheels. Check your owner's manual or a dealer.

Is tire height the same as tire diameter?

Yes: tire height and overall tire diameter are the same measurement: the outer diameter of the fully inflated, mounted tire from contact patch to top. Both terms describe the same dimension. 'Height' is the informal term most people use, especially for off-road and lifted-truck applications (e.g., 'a 33-inch tire'). 'Overall diameter' is the engineering term used in manufacturer documentation and ISO/SAE standards.

How do I calculate tire height in inches from a metric size?

Use this three-step process: (1) Sidewall height in mm = Width × (Aspect ÷ 100). (2) Convert to inches: divide by 25.4. (3) Total height = rim diameter + 2 × sidewall in inches. Example for 225/65R17: sidewall = 225 × 0.65 = 146.25 mm = 5.76 in. Total height = 17 + 2 × 5.76 = 28.52 in. The Metric Size tab of this calculator performs this automatically and displays both the inch and mm results.

What metric tire size equals a 33-inch tire?

Metric sizes near 33 inches on a 17-inch rim are 285/75R16 (32.83 in) and 275/70R18 (33.16 in). On a 17-inch rim, 285/70R17 measures 32.71 in and 315/70R17 measures 34.36 in. On an 18-inch rim, 275/65R18 comes in at 32.07 in and 285/65R18 at 32.59 in. The Find by Height tab scans all combinations ±2% of 33 inches for any rim size you choose.

Does a taller tire improve ground clearance?

Yes: every 2 inches of additional total height raises ground clearance at the axle center by exactly 1 inch, since the axle sits at the tire's radius. A 33-inch tire gives 16.5 in of ground clearance (at the axle), while a 35-inch tire gives 17.5 in. This calculation only applies to the axle-level clearance: actual body/frame clearance also depends on suspension lift, wheel offset, and the physical space in the wheel well.

How does tire height affect speedometer reading?

A taller tire has a larger circumference and travels further per revolution, so the wheel makes fewer revolutions per mile. Speedometers count wheel revolutions and multiply by the expected circumference: if the circumference is larger than expected (bigger tire), the speedometer reads lower than your actual speed. Formula: True Speed = Indicated Speed × (New Height ÷ OEM Height). A tire 5% taller than OEM means your speedometer reads 50 mph when you are actually doing 52.5 mph.

What is the difference between sidewall height and total tire height?

Sidewall height is only the tire's rubber section: from the rim bead to the outer tread. Total height (overall diameter) is the complete measurement from ground to top, which equals the rim diameter plus two sidewall heights (one top, one bottom). For a 225/45R17: sidewall = (225 × 0.45) ÷ 25.4 = 3.99 in. Total height = 17 + 2 × 3.99 = 24.97 in. The aspect ratio in a P-metric code is the sidewall-height-to-width ratio, not the full height.

How do I find the correct tire size for a target total height?

Use the Find by Height tab: enter your target in inches and your rim size, and the calculator scans all standard metric widths (155–315 mm) and aspect ratios (30–80) to return every size within ±2% of your target. Results are sorted by closest match. This is the fastest way to find a metric equivalent for a floatation inch target (e.g., "I want a 35-inch tire on 18-inch rims").

Do wider tires have a different height than narrower tires with the same aspect ratio?

Yes: aspect ratio is a percentage of section width, so a wider tire with the same aspect ratio has a taller sidewall and a larger total height. For example, a 225/65R17 has a sidewall of (225 × 0.65) ÷ 25.4 = 5.76 in and a total height of 28.52 in. A 265/65R17 has a sidewall of (265 × 0.65) ÷ 25.4 = 6.78 in and a total height of 30.55 in: over 2 inches taller despite both using a 65-series aspect ratio and the same 17-inch rim.

Tire Height Calculator: Total Tire Height in Inches or mm (2026)

QUICK EXAMPLE

A 265/70R17 tire has a total height of 31.61 inches (calculated: 17 + 2 x 7.30). A 285/75R17 is 33.83 inches, a +7.0% increase, beyond the 3% rolling circumference limit in Continental's guidance. Use the comparison tab below to check the exact height difference and speedometer correction for your own sizes.

Metric · Inches · Compare · Find

InchesMetric

Tire Height Calculator: Metric Size (P-Metric)

Common sizes: quick load:

Tire Size (e.g. 225/65R17)

Pre-Computed Heights: 12 Popular Metric Sizes

Height (in)	Height (mm)	Sidewall (in)	Circumference (in)	Revs/Mile	Category
24.47″	621.5	4.73″	76.87″	824	Economy sedan
24.98″	634.5	4.99″	78.48″	807	Compact
24.88″	631.9	4.44″	78.16″	811	Midsize sedan
26.16″	664.4	5.08″	82.18″	771	Family car
24.97″	634.3	3.99″	78.45″	808	Sport sedan
28.52″	724.3	5.76″	89.58″	707	Crossover / SUV
28.18″	715.7	5.09″	88.52″	716	Mid-size SUV
26.68″	677.7	4.34″	83.82″	756	Performance
31.61″	802.8	7.30″	99.29″	638	Truck / light off-road
32.07″	814.7	7.04″	100.77″	629	Half-ton truck
32.83″	833.9	8.42″	103.14″	614	Jeep / off-road
34.36″	872.8	8.68″	107.95″	587	Lifted truck

Click any size to load it into the calculator above.

How to Use This Calculator

1Tab 1: Metric Size: Type your P-metric tire code (e.g. 225/65R17) or click a preset. Click "Calculate Height" to see total height, sidewall, circumference, and revs/mile in both inches and mm.
2Tab 2: Inches Direct: Enter the rim diameter and the tire sidewall height in inches. Use this for floatation sizes (35×12.5R17), trailer tires, or any tire where you have a physical measurement. The mm↔inch reference table is expandable below.
3Tab 3: Compare Two: Enter Size A (your current/OEM tire) and Size B (your proposed new tire). The calculator outputs height delta, size-change badge (small change / within 3% / beyond 3% / large change), a visual SVG comparison, and a per-speed speedometer correction table.
4Tab 4: Wheel + Tire Total: Enter wheel rim diameter and one sidewall height in inches to see the complete assembled height: useful for custom builds, trailers, and ground-clearance planning.
5Tab 5: Find by Height: Enter a target height in inches and a rim size. The calculator scans over 1,000 standard metric combinations and returns every size within ±2%, sorted by closest match.
6Global: Use the Inches/Metric toggle (top right) to switch all displayed results between imperial and metric. Click "Copy Results" to copy the current calculation to your clipboard.

Tire Height Reference Table: 12 Popular Sizes

Size	Height (in)	Height (mm)	Sidewall (in)	Circumference (in)	Revs / Mile	Named in
185/65R15	24.47″	621.5	4.73″	76.87″	824	Calculated
195/65R15	24.98″	634.5	4.99″	78.48″	807	Calculated
205/55R16	24.88″	631.9	4.44″	78.16″	811	Calculated
225/45R17	24.97″	634.3	3.99″	78.45″	808	Calculated
225/65R17	28.52″	724.3	5.76″	89.58″	707	Calculated
245/65R17	29.54″	750.3	6.27″	92.80″	683	Acadia 2020 manual
265/70R17	31.61″	802.8	7.30″	99.29″	638	Tacoma (Toyota 2025 manual), F-150 XL 4x4 (Ford 2026)
275/65R18	32.07″	814.7	7.04″	100.77″	629	F-150 4x4 (Ford 2026), Sierra 1500 LT (GMC manuals)
285/75R16	32.83″	833.9	8.42″	103.14″	614	Calculated
305/55R20	33.21″	843.5	6.60″	104.33″	607	Calculated
315/70R17	34.36″	872.8	8.68″	107.95″	587	Closest metric size to 35x12.50R17

Heights are calculated from ISO/SAE P-metric standard formulas. The 35×12.5R17 floatation size uses nominal inch dimensions. All values assume standard inflation pressure: actual dimensions may vary ±1–2% by manufacturer.

Inch-to-Metric Tire Height Quick Reference

Target Height	Rim	Closest Metric Size	Actual Height	Δ from Target	Application
26″	17″	215/65R17	27.48″	+1.48″	Stock SUV / crossover
28″	17″	225/65R17	28.52″	+0.52″	Crossover upgrade
29″	17″	235/65R17	29.00″	+0.00″	Compact truck
30″	17″	245/70R17	30.47″	+0.47″	Full-size car / minivan
31″	17″	265/70R17	31.61″	+0.61″	Light truck (Tacoma, Frontier)
33″	17″	285/75R17	32.83″	-0.17″	Mild off-road (Jeep JK)
33″	20″	275/65R20	33.06″	+0.06″	Modern truck 20″ wheel
35″	17″	315/70R17	34.36″	-0.64″	Heavy off-road (TRD Pro)
35″	20″	295/70R20	34.26″	-0.74″	Lifted truck 20″ wheel
37″	17″	355/70R17	37.14″	+0.14″	Extreme off-road

Use the Find by Height tab in the calculator above for a full scan: this table shows the single closest match per target; the tab returns all sizes within ±2%.

Tire Height Formulas: Complete Reference

Tire Height Formulas: Complete Reference

1. TOTAL HEIGHT FROM P-METRIC CODE (e.g. 265/70R17)
   Step 1: Sidewall Height (mm):
     Sidewall_mm = Section Width × (Aspect Ratio ÷ 100)
     = 265 × 0.70 = 185.5 mm

   Step 2: Sidewall Height (inches):
     Sidewall_in = 185.5 ÷ 25.4 = 7.303 in

   Step 3: Total Height (Overall Diameter):
     Total_Height = Rim_Diameter + 2 × Sidewall_in
     = 17 + 2 × 7.303 = 31.61 in  (802.9 mm)

2. TOTAL HEIGHT: INCH-DIRECT METHOD
   Total_Height = Rim_Diameter + 2 × Sidewall_Height
   Example: 35×12.5R17:
     Total_Height = 17 + 2 × 8.875 = 34.75 in

3. CIRCUMFERENCE
   C = π × Total_Height
   C = 3.14159 × 31.61 = 99.29 in  (2.522 m)

4. REVOLUTIONS PER MILE
   Rev/Mile = 63,360 ÷ Circumference_in
   = 63,360 ÷ 99.29 = 638 rev/mi

5. REVOLUTIONS PER KM
   Rev/km  = 39,370 ÷ Circumference_in
   = 39,370 ÷ 99.29  = 396 rev/km

6. HEIGHT DIFFERENCE % (COMPARISON)
   Δ% = ((New_Height − OEM_Height) ÷ OEM_Height) × 100
   Example: 285/75R16 vs 265/70R16:
   = ((32.83 − 30.55) ÷ 30.55) × 100 = +7.5%

7. SPEEDOMETER CORRECTION
   True_Speed = Indicated_Speed × (New_Height ÷ OEM_Height)
   If New > OEM → speedometer reads LOW (true speed is higher).
   If New < OEM → speedometer reads HIGH (true speed is lower).

8. REPLACEMENT WINDOW (CONTINENTAL 3% GUIDANCE)
   Max_Height = OEM_Height × 1.03
   Min_Height = OEM_Height × 0.97
   Continental advises keeping rolling circumference within 3% of the original. It is not a vehicle maker specification; most owner's manuals publish no percentage.

9. GROUND CLEARANCE AT AXLE
   Axle_Height = Total_Height ÷ 2 (the tire radius)
   Every +2 in of total height = +1 in ground clearance at the axle center.

P-Metric decoding: The three numbers in a P-metric tire code (e.g. 265/70R17) encode everything needed to calculate height. The first number is section width in millimetres; the second is the aspect ratio: sidewall height as a percentage of width; the third is the rim diameter in inches. The inconsistent unit system (mm width, % aspect ratio, inch rim) is a historical accident from the 1960s metrication of tire standards, but the formula is straightforward once you know the conversion factor of 25.4 mm per inch.

Tire height vs tire diameter: Both terms describe identical measurements: the outer diameter of a mounted, inflated tire from contact patch to the diametrically opposite point on the tread. Engineers and tire manufacturers use “overall diameter”; enthusiasts and off-road communities use “height”. You will encounter both in spec sheets: they are always the same number. The overall height from a P-metric size and the sidewall height by width and aspect ratio each isolate one part of this.

The 3% limit: Continental advises keeping the rolling circumference within 3% of the original. It is not a vehicle maker specification; most owner's manuals publish no percentage and ask for the same size and type on all four wheels. The Compare tab labels changes as small (<1%), within 3% (1–3%), beyond 3% (3–5%) and large (>5%); only the 3% edge is sourced.

Aspect ratio and total height: A common misconception is that the aspect ratio alone determines tire height. In fact, two tires with the same aspect ratio can have very different heights if their widths differ. A 225/65R17 (5.76 in sidewall → 28.52 in total) and a 265/65R17 (6.78 in sidewall → 30.55 in total) both carry a 65-series aspect ratio but the wider tire is over two inches taller. Always calculate from the full three-number code, not the aspect ratio alone. To work backwards from a target height, the aspect ratio solver finds the ratio that fits, and the side-by-side tire height chart shows two sizes at the same scale.

Tire Height Calculator