Tire Size Comparison Calculator: Visual Profiles, Diameter Matcher, and Plus-Size Finder
Built and reviewed by David (MBA Finance) · Updated October 2026
The only free tire comparison tool that draws your tire sizes to scale as visual profiles side by side, compares up to three sizes at once with compatibility ratings, finds every metric size matching a target diameter, and shows plus-size options on a new rim while preserving your original diameter.
📏 Select Comparison Mode
🔵 Tire 1 (Baseline / Stock)
🔴 Tire 2 (New / Option A)
🟢 Tire 3 (Option B: Optional)
🔍 Find All Sizes Matching a Target Diameter
Or enter the target diameter below. If both are filled, tire code takes priority.
in
📈 Current Tire Size
🛞 New Rim Diameter
in
Example: moving from 16″ to 17″ rims. The calculator finds metric sizes on 17″ rims that match your current 31.6″ diameter.
📊 Comparison Results
📏
Enter two or three tire sizes to see a visual profile comparison, full spec table, speedometer error, and compatibility rating. Or use Diameter Match to find all metric sizes near a target diameter.
Tire Dimension Comparison
Why Tire Size Comparison Matters Before You Buy New Rubber
Buying tires in the United States sounds simple until you realize the metric code on your door jamb does not tell you how tall the tire is, how wide it is in inches, or whether an alternative size will fit your truck without rubbing the fender liner. The number printed on the sidewall only makes sense once you know the formula behind it. And once you start shopping alternatives, wider options for better off-road grip, lower-profile options for sharper handling, or plus-sized rims with matching tires, you need a fast way to see exactly what changes and by how much.
That is what this calculator solves. The 3-Way Comparison mode lets you put your current tires and two alternatives side by side with visual profiles drawn to the actual proportional scale so you can immediately see which is taller, which is wider, and by how much. The Diameter Matcher answers the question that no other single tool addresses well: given a tire I want to replace, what are every single standard metric size that has essentially the same overall diameter? The Plus-Size Finder handles the classic rim upgrade scenario, you bought 18-inch wheels but your stock tires were on 16-inch rims, so what metrics fit the 18-inch rim while keeping your speedometer reading correctly?
What the Compatibility Rating Means
Every comparison in this tool shows a color-coded compatibility rating based on the percentage diameter difference from Tire 1 (your baseline). SAFE in green means the diameter difference is 2 percent or less, within factory speedometer calibration tolerance. CAUTION in orange means 2 to 5 percent, your speedometer will read off enough to notice on a GPS check, and your transmission shift points and ABS calibration will be slightly off. RECAL REQUIRED in red means over 5 percent difference, this level of diameter change requires reprogramming your vehicle’s PCM or ABS module, and in some cases affects warranty-covered safety systems.
How the Three Comparison Modes Work in Real-World Situations
The 3-Way Comparison Visual Profile: See It Before You Buy It
The visual tire profile is the feature no US competitor provides. When you enter three tire sizes, this calculator draws each one as a proportional cross-section rectangle, the width scaled to section width, the height scaled to overall diameter, with the rim circle shown inside in dashed lines. All three profiles share the same scale axis, so you can immediately see that a 285/75R17 is physically taller and wider than a 265/70R17, while a 295/70R17 is wider but not quite as tall. No amount of reading numbers makes this as clear as seeing the visual shapes side by side.
Diameter Matcher: “Just Find Me Everything That is Basically This Size”
This mode solves the situation where a tire shop discontinued your exact size and wants to substitute something close, or where you want to explore width options at the same height for your truck build. Enter 265/70R17 as the reference and search with half-inch tolerance on any 17-inch rim, and you get every standard metric size between 31.1 and 32.1 inches total diameter on 17-inch wheels, sorted from closest to furthest. This is how professional tire shops cross-reference sizes when a specific model is on back-order.
Plus-Size Finder: 16-inch to 17-inch, 17-inch to 18-inch, Any Combination
Plus-sizing is the practice of stepping up rim diameter while reducing aspect ratio to maintain the same overall tire diameter. The math is straightforward but tedious to do manually for every candidate size. Enter your current 205/55R16 and your target 17-inch rim, and the Plus-Size Finder instantly returns every standard metric size on a 17-inch rim that maintains a diameter within 0.75 inches of your stock 24.88-inch diameter, sorted by speedometer error so you can pick the option with the smallest impact on your vehicle’s calibration.
Three Real US Tire Comparison Scenarios Calculated
Scenario 1: Ram 1500 Owner Comparing Three Tire Options for an Overlanding Build
The 2022 Ram 1500 Big Horn comes from the factory on 275/65R18 tires. A buyer planning a light overlanding build is comparing three options: keeping stock, moving to 285/65R18 (a tiny upsizing), or going to 285/70R17 (same width but taller, with a rim downsize from 18 to 17 inch).
Spec
275/65R18 (Stock)
285/65R18
285/70R17
Diameter
32.07″
32.59″
32.71″
Section width
10.83″
11.22″
11.22″
Sidewall height
7.04″
7.30″
7.86″
Rev/mile
631
621
619
Speedo error vs stock
baseline
+1.62%
+2.00%
Compatibility
Baseline
SAFE (under 2%)
SAFE (exactly 2.0%)
All three options fall within the SAFE 2 percent diameter threshold, meaning no speedometer recalibration is required. The 285/70R17 adds the most sidewall height (0.82 inches per side) which improves off-road articulation significantly for overlanding use. However, moving from 18-inch to 17-inch rims requires purchasing a separate set of 17-inch wheels, which adds cost but also allows the owner to pair them with an All-Terrain tire that has better trail-rated selection in 17-inch sizing than in 18-inch.
Scenario 2: Honda CR-V Owner Finding Same-Diameter Alternatives for a Discontinued Size
A 2019 Honda CR-V EX runs 235/60R18 tires (30.15-inch diameter). The owner’s tire shop says the OEM replacement is back-ordered six weeks but has similar sizes in stock. The Diameter Matcher finds all alternatives within 0.5 inch of the 30.15-inch target on 18-inch rims.
Tire Size
Diameter
Diff from Stock
Width
Speedo Error
225/65R18
30.47″
+0.32″
8.86″
+1.05%
235/60R18
30.15″
exact
9.25″
0.00%
245/60R18
30.54″
+0.39″
9.65″
+1.30%
255/55R18
29.88″
-0.27″
10.04″
-0.91%
The 225/65R18 is 0.32 inches larger in diameter (1.05% speedometer error) and slightly narrower, making it a safe substitute while the OEM size is on backorder. The 245/60R18 is a reasonable choice too if the tire shop has a preferred brand available only in that size. Both are within the SAFE 2 percent threshold. The 255/55R18 is the closest negative match, slightly smaller diameter meaning the speedometer reads 0.91% fast (it was already reading slightly fast from the factory, so this actually improves absolute accuracy on some vehicles).
Scenario 3: Civic Owner Using the Plus-Size Finder for a Wheel Upgrade
A Honda Civic Sport Hatchback runs 235/40R18 (26.35-inch diameter). The owner found a deal on 19-inch aftermarket wheels and wants to know what metric tires on 19-inch rims will keep the Civic’s diameter close to stock for a clean plus-one sizing.
Plus-Size Option
Diameter
Width
Speedo Error
Rating
235/35R19
26.07″
9.25″
-1.07%
SAFE
245/35R19
26.47″
9.65″
+0.45%
SAFE
225/40R19
26.85″
8.86″
+1.89%
SAFE
Best pick
245/35R19
9.65″
+0.45%
Closest diameter, negligible error
The 245/35R19 is the closest in diameter to stock (only 0.45% speedometer error) while also being 0.4 inches wider than the 235/40R18, improving lateral grip slightly. The 235/35R19 is the most conservative choice if maintaining OEM width is important, with a minor -1.07% error (reads slightly fast). All three options are within the SAFE range. The lower-profile 35-series sidewall on the 19-inch rim gives the Civic a sportier stance but reduces sidewall cushioning on rough roads, the tradeoff that comes with any rim size increase.
Three Things Tire Shops Do Not Tell You Before You Plus-Size
Tip 1: Wider Tires on the Same Rim May Need a New Rim
Stepping from 235mm to 265mm section width does not necessarily require new rims, but it does require that the rim width falls within the tire’s approved rim width range. A 265mm tire typically specifies 7.5 to 9.5 inches of rim width. If your current 17-inch rims are only 7 inches wide, common on smaller trucks and base-trim SUVs, the wider tire will technically mount but will flare outward abnormally, creating a balloon-like profile that reduces the contact patch quality and can cause edge wear on the outer tread blocks. Tire manufacturers publish rim width compatibility tables for every tire model. Check the specific tire you are buying before assuming the same rims work for a significantly wider tire.
The second consideration is wheel offset. Plus-sizing to larger diameter rims is often done with aftermarket wheels that have a different offset (ET value) than the OEM wheels. A lower offset (more negative, or “more backspacing”) pushes the wheel further out from the hub, which can cause the tire to stick out past the fender or create clearance problems with the suspension. A higher offset (less negative) pushes the wheel in, which can cause the tire to contact the inner fender or brake components. The Wheel Offset Calculator in the Auto Hub handles this calculation separately once you have your rim upgrade defined.
Tip 2: The Visual Profile Difference Is Smaller Than You Expect
A common surprise when drivers first look at the visual tire profile comparison is how modest the difference looks between a 265/70R17 and a 285/75R17, even though the latter is over an inch taller. The reason is that both tires are several times wider than their diameter difference, so on the visual scale the height increase looks proportionally small. This is actually useful information: it tells you that in the real world, a one-inch height increase on a 31-inch tire (about 3 percent) is indeed a modest physical change. The truck owner who expects their vehicle to look dramatically different after upgrading from 265/70R17 to 285/75R17 may be surprised at how similar the actual stance change is compared to what the forum photos suggested. The 3.86 percent diameter increase means the truck sits about 0.61 inches higher, visible, but subtle without a lift kit to accompany it.
Tip 3: Diameter Matching Is More Important for All-Wheel Drive Vehicles
On a standard two-wheel drive vehicle, running mismatched tire diameters front to rear or side to side is primarily a handling issue, it changes understeer/oversteer balance and causes uneven wear. On an all-wheel drive or four-wheel drive vehicle, it is a mechanical issue that can damage expensive components. AWD systems distribute torque between axles through a center differential or coupling that assumes both axles are rotating at the same speed. If the front and rear tires have different diameters (even from mixing two otherwise-similar sizes), the axles rotate at different speeds during straight-ahead travel, causing the AWD coupling to continuously slip. Over time this overheats the transfer case or center differential. Tire manufacturers, vehicle manufacturers, and the Consumer Federation of America all recommend that AWD vehicles use tires within 1/32 inch of tread depth on all four corners, and this applies equally to overall tire diameter. If you upgrade two tires at a time, always put new tires on both wheels of the same axle together, and use the Diameter Matcher to ensure any alternative size matches your other tires within the tightest practical tolerance.
16 Tire Size Comparison FAQs for US Drivers and Truck Builders
Enter both tire codes in the 3-Way Comparison mode and hit Compare. The tool shows overall diameter for each, the difference in inches, and a visual profile drawn to scale. For example, a 285/75R17 has a 32.83-inch diameter while a 265/70R17 is 31.61 inches, making the 285 series 1.22 inches taller. The calculator also shows the ride height change (0.61 inches higher per side) and whether the difference is within the SAFE compatibility threshold for your speedometer and ABS systems.
These ratings reflect the percentage diameter difference from your baseline tire. SAFE (green) means the diameter difference is 2 percent or less, within the calibration buffer already built into factory speedometers. A US-spec speedometer is allowed by federal regulation to read up to 10 percent fast, and manufacturers typically calibrate 2 to 4 percent fast from the factory, so a 2 percent tire upsizing usually stays within the speedometer’s acceptable range. CAUTION (orange) is 2 to 5 percent, your GPS-verified speed will noticeably diverge from your speedometer, and your transmission shift points and ABS threshold speeds will be slightly off. RECAL REQUIRED (red) is over 5 percent, mandatory PCM or ABS recalibration is needed to restore safe system operation. For comparison: a 265/70R17 to 285/75R17 upgrade is 3.86 percent (CAUTION). A 255/75R17 Jeep stock tire to a 37-inch tire is 15 percent (hard RECAL).
Yes, this is exactly what the Diameter Matcher is designed for. Enter your current tire code as the reference, set tolerance to 0.5 inch, and optionally lock to your current rim diameter. The tool returns every standard metric size within that range, sorted by closeness. You can then cross-reference which sizes your tire shop carries in stock. For a CR-V running 235/60R18 with a 30.15-inch diameter, the tool finds 225/65R18, 245/60R18, and 255/55R18 as near-matches on the same 18-inch rims, all within 0.4 inch of stock diameter and under 1.5 percent speedometer error.
Plus sizing is a system for upgrading wheel diameter while reducing tire aspect ratio to maintain the same overall tire diameter. Plus-zero means keeping the same rim diameter but fitting a wider tire, without aspect ratio adjustment. Plus-one means increasing rim diameter by 1 inch (e.g., 16 to 17) while reducing the aspect ratio by approximately 5 to 8 points to keep total diameter the same. Plus-two increases rim diameter by 2 inches (e.g., 16 to 18) with a proportionally greater aspect ratio reduction. The goal in each case is to keep the total tire diameter within 1 to 3 percent of stock. Use the Plus-Size Finder mode to calculate which metric sizes on your new rim diameter maintain the same diameter as your current setup.
The 275/65R18 has a diameter of 32.07 inches, while the 275/60R20 has a diameter of 32.99 inches, so the 275/60R20 is actually 0.92 inches taller despite both being 275mm wide. The larger rim diameter on the 20-inch wheel more than compensates for the lower 60 aspect ratio versus the 65. Enter both codes in the 3-Way Comparison mode to see the full breakdown: same section width (10.83 inches), but the 18-inch tire has a 7.04-inch sidewall while the 20-inch tire has a 6.50-inch sidewall, shorter sidewall, larger rim, net taller tire. This is a common surprise that catches drivers off guard when comparing across different rim sizes.
The visual profiles are drawn from the mathematical specifications of the tire code, section width, aspect ratio, and rim diameter. Actual tire brands may vary slightly from these calculated dimensions due to manufacturer tolerances. The tire industry standard allows actual section width to vary from the nominal by approximately plus or minus 4 percent, and actual overall diameter by plus or minus 2 percent. A Michelin 265/70R17 and a BFGoodrich 265/70R17 will be very close to each other and to the calculated dimensions but may not be exactly the same. The profiles in this calculator show the mathematically-specified sizes, which is accurate enough for purchasing decisions. For precise fitment clearance measurements, always verify with the specific tire manufacturer’s published dimensions.
The Diameter Matcher searches across a predefined list of common US-market metric tire widths (195mm through 335mm in standard increments) and common aspect ratios (35 through 85 in 5-point increments) on rims from 14 to 22 inches. Sizes that fall outside these parameters, very narrow tires below 195mm, very wide tires above 335mm, unusual aspect ratios like 30 or 55 on uncommon rim sizes, or very large rims like 24 or 26 inches, are not in the search space. For specialty applications (lifted trucks on 24-inch wheels, European vehicle sizes, commercial van tire sizes), you can also use the 3-Way Comparison by manually entering any valid combination of width, aspect ratio, and rim diameter.
Aspect ratio directly determines sidewall height, and sidewall height determines the cushion of air between the road and your rim. A 70-series tire on a 17-inch rim has approximately 7 inches of sidewall, substantial pneumatic cushioning that absorbs road irregularities before they reach the rim. A 35-series tire on an 18-inch rim has approximately 3.5 inches, much less flex and cushion. In practical terms, low-profile tires transmit road texture, expansion joints, and potholes more directly into the cabin. On smooth pavement this is barely noticeable. On typical US urban roads with aging asphalt and pothole exposure, the difference is significant enough that drivers coming from a 65-series truck tire to a 45-series performance tire often describe the low-profile setup as noticeably harsher. The visual comparison helps quantify exactly how much sidewall you are gaining or losing with any size change.
For two-wheel drive vehicles, mixing sizes front to rear is generally not recommended because it changes handling balance, but it is not mechanically damaging. Running different sizes on the same axle (left vs right) is never acceptable because it creates a constant pull toward the smaller tire side and causes uneven brake force during stops. For all-wheel drive and four-wheel drive vehicles, matching all four tires to within 1/32 inch of tread depth (and by extension, the same overall diameter) is critical to avoid overheating AWD couplings and damaging differentials. If this comparison shows a diameter difference greater than 0.5 percent between two sizes, do not run one on the front and the other on the rear of an AWD vehicle.
The relationship between tire diameter and fuel economy is more nuanced than most forum posts suggest. A larger diameter tire covers more distance per revolution, which in theory reduces engine RPM at a given highway speed, a fuel efficiency benefit on vehicles whose engine is most efficient at a slightly lower RPM than the stock tire puts it in top gear. This explains why some diesel truck owners report 1 to 2 MPG gains after a 3-percent tire upsizing. However, a wider tire (larger section width) increases rolling resistance due to a larger contact patch, and a heavier tire requires more energy to accelerate and decelerate. The net effect for most gasoline-engine vehicles upgrading from stock 265/70R17 to 285/75R17 is a slight fuel economy penalty of 0.5 to 1.5 MPG, particularly in city driving. The US Department of Energy fuel economy maintenance tips at fueleconomy.gov note that proper tire inflation is the single biggest tire-related factor in fuel economy, outweighing size differences for most drivers.
There is no universally agreed federal standard for maximum allowable speedometer error after a tire size change, but the practical thresholds used by professional truck builders and performance tuners are: under 2 percent is acceptable without concern, 2 to 3 percent is within typical factory calibration range and generally considered acceptable, 3 to 5 percent is where most manufacturers recommend recalibration, at this level your transmission shift points, ABS activation thresholds, and adaptive cruise control are all working from stale wheel-speed data, and the speedometer error is large enough to be a legitimate traffic safety concern on highways where you may unknowingly be driving 4 to 5 mph over the indicated speed, and above 5 percent is universally considered to require recalibration before the vehicle should be driven on public roads at highway speeds.
Revolutions per mile is the number of times each wheel rotates for every mile of travel. A smaller tire has a shorter circumference and rotates more times per mile. A larger tire rotates fewer times per mile. This number matters for three reasons: odometer accuracy (an odometer counts wheel revolutions and multiplies by tire circumference, if the circumference changed, the odometer is wrong), gear ratio selection (when building an off-road truck, the gear ratio calculation uses tire circumference to set the correct axle ratio for the engine’s power band), and ABS calibration (the ABS module compares individual wheel rotation rates to detect skidding, the rate it expects is calibrated to the stock tire’s revolutions per mile). When comparing tires, a difference of more than 25 revolutions per mile (about 3 to 4 percent) is significant enough to affect all three of these systems.
285mm divided by 25.4 equals 11.22 inches. 265mm divided by 25.4 equals 10.43 inches. The difference is 0.79 inches. This is the section width difference, the widest point of the tire measured at the sidewall. The actual tread contact patch width may be slightly narrower than the section width, depending on the tire’s construction and the rim width it is mounted on. A narrower rim causes the tire to pinch inward slightly, reducing the effective tread width. A wider rim spreads the tread slightly. For practical fender clearance calculations, use the section width difference (0.79 inches) as your reference, which means the tire is 0.39 inches wider on each side of the rim centerline.
Yes. The dimensional math for LT-metric and P-metric tires of the same width/aspect/rim combination is identical, both a P265/70R17 and an LT265/70R17 have the same nominal diameter, section width, and sidewall height. The difference between LT and P designations is in load rating and construction (LT tires have heavier ply construction and higher maximum load capacity), not in external dimensions. Enter any tire code with or without the LT or P prefix and the comparison will work correctly. Load range ratings (C, D, E on LT tires) do not affect the dimensional calculations and are not factored into this comparison tool.
The most frequently compared US truck tire pairs, based on common forum upgrade discussions: 265/70R17 vs 285/75R17 (the most popular F-150 upgrade, 3.86% larger), 275/65R18 vs 285/65R18 (Ram 1500 mild upgrade, 1.62% larger), 255/75R17 vs 285/75R17 (Jeep Wrangler width upgrade on stock rim, 3.69% larger), 265/70R17 vs 275/70R17 (conservative width upgrade, 1.0% larger), 275/55R20 vs 285/55R20 (Silverado/Sierra upgrade, 0.78% larger). Try any of these pairs in the 3-Way Comparison to see the full visual profile and speedometer error before making a purchase decision.
These calculations use the Tire and Rim Association (TRA) standard formulas: sidewall height = section width x (aspect ratio / 100); overall diameter = (2 x sidewall height in inches) + rim diameter. These formulas are the same ones used by all major tire manufacturers for their published specifications. The Rubber Manufacturers Association (RMA), which sets US tire standards, and the TRA both specify that actual mounted tire dimensions may vary from nominal by up to 4 percent in section width and 2 percent in overall diameter due to manufacturing tolerances, rim width variation, and inflation pressure. For the purposes of comparing tire sizes to make upgrade decisions, the calculated dimensions are accurate to within 0.5 inch in diameter and 0.3 inch in width, more than sufficient precision for speedometer error estimates, fender clearance planning, and plus-sizing decisions.
Tire dimension calculations use TRA-standard formulas. Sidewall height equals section width multiplied by aspect ratio divided by 100. Overall diameter equals two sidewall heights in inches plus rim diameter. These formulas match published specifications within manufacturing tolerance (plus or minus 2 percent in diameter, plus or minus 4 percent in section width per RMA standards). Speedometer error is calculated as the percentage difference in diameter from the baseline tire. Compatibility ratings (SAFE/CAUTION/RECAL REQUIRED) reflect common industry thresholds and are provided for informational purposes only, actual vehicle system behavior depends on the specific vehicle’s ECU calibration, ABS module, and manufacturer tolerances.
Actual fender clearance, wheel offset compatibility, AWD system requirements, and TPMS programming are vehicle-specific and must be verified with your vehicle manufacturer’s documentation and a qualified tire professional. Editorial transparency: This calculator is provided free with no advertising from tire brands, wheel manufacturers, or retailers. No payment was accepted to influence the content, featured tire sizes, or compatibility thresholds shown here.