Overall Diameter
+0.47 in
+1.58%
29.57 in30.04 in
245/60R18 vs 255/55R19 Tire Size Comparison
245/60R18 vs 255/55R19: overall diameter changes by +0.47" (+1.58%), section width changes by +10 mm, sidewall height changes by −0.27", and static ground clearance shifts by about +0.23 in. Speedometer impact is about +1.58% at 60 mph indicated. This pair requires a different wheel diameter (18" → 19"). These figures are dimensional calculations only — they do not confirm vehicle fitment.
Tire Size Comparison Calculator
Key Specification Differences
Section Width
+0.39 in
+4.08%
9.65 in10.04 in
Sidewall Height
−0.27 in
-4.59%
5.79 in5.52 in
Circumference
+1.47 in
+1.58%
92.91 in94.38 in
Speedometer & Revs-per-Mile Impact
Speedometer Difference
+1.58%
+1.58%
60 mph61.0 mph true
Revolutions per Mile
−11
-1.56%
681.9671.3
Side-by-side proportional comparison of Original tire 245/60R18 and New tire 255/55R19 on a shared ground baseline. Overall diameter 29.57" versus 30.04" (difference +0.47"). Section width 9.65" versus 10.04". Wheel diameter 18" versus 19".
Diameter 29.57" → 30.04" (+0.47")Width 9.65" → 10.04"Wheel 18" → 19"
Comparison uses nominal dimensions calculated from the selected tire sizes. Actual manufacturer measurements may differ.
- Steering responseShorter sidewall may reduce flex, although tire construction, pressure and vehicle setup also affect response.
- Ride comfortShorter sidewall generally transmits more impact harshness.
- Sidewall complianceReduced sidewall height typically means less vertical compliance over sharp edges; construction still matters.
- Effective gearingThe larger rolling diameter produces slightly taller effective gearing.
- Road-use characterWidth and profile changes can alter road feel and noise; they do not by themselves prove better grip, snow performance or towing ability.
Driving & Vehicle Impact
Speedometer at selected speed
60 mph indicated ≈ 61.0 mph actual
Based on the selected vehicle-speed input.
Ground-clearance effect
Approximately +0.23"
Half of the overall diameter increase.
Sidewall behaviour
Shorter sidewall
May reduce flex and increase impact harshness.
Effective gearing
Approximately +1.58% taller
Slightly fewer wheel revolutions per road mile.
Wheel requirement
19-inch wheel required
The original 18-inch wheel cannot be reused.
Installation complexity
Moderate verification required
Wheel, load, clearance and offset checks remain.
Checks Triggered by This Comparison
Replacement wheel required
- 255/55R19 requires a 19" wheel
- The 18" wheel used by 245/60R18 cannot be reused
Larger envelope check
- Section width increases +10 mm
- Overall diameter increases +0.47"
- Verify fender and suspension clearance at full lock and compression
The ±3% diameter threshold is a comparison screen, not confirmed vehicle fitment.
Alternative Comparison Paths
Alternative sizes are dimensional comparisons only. Verify wheel width, load rating, offset and vehicle clearance.
What changes when switching from 245/60R18 to 255/55R19?
Plus-sizing and wheel use
This is a plus-size change from a 18" to a 19" wheel.
The 18" wheel cannot be reused for the 19" tire.
+1.58% diameter change is inside the site’s ±3% comparison threshold.
Dimensional direction
255/55R19 is taller than 245/60R18 (+0.47") and wider (+10 mm).
Sidewall height decreases by 0.27"; static ground clearance increases by 0.23".
Road speed, revs and gearing
Theoretical road speeds: 30 indicated = 30.5 mph actual; 60 indicated = 61.0 mph actual; 75 indicated = 76.2 mph actual.
Revolutions per mile change −10.6 (-1.56%), producing taller effective gearing.
Tire models sold in both sizes
8 indexed brand/model names exist in both sizes: Falken AKLIMATE, Falken WILDPEAK A/T TRAIL, Falken ZIEX CT60 A/S, Goodyear ProControl®, plus 4 more. Service descriptions and specifications can differ by size.
Popular Tires Available in 255/55R19
Performance
Eagle F1 All Season
255/55R19 · 111Y · Load Range XL
All-Terrain
Open Country A/T III
255/55R19 · 111H · Load Range XL
Highway Terrain
Ziex CT60 A/S
255/55R19 · 111V · Load Range XL
Performance
Eagle F1 Asymmetric 6
255/55R19 · 111W · Load Range XL
Highway Terrain
Open Country Q/T
255/55R19 · 111V · Load Range XL
Highway Terrain
Ziex CT60 A/S
255/55R19 · 111V · Load Range XL
Models shown are matched to exact-size records in TireReference's tire database. Availability and specifications may change; confirm with the manufacturer or retailer. Data and Calculation Standards
Popular Comparison Pairs
Common size upgrades from the Tire Reference database.
Frequently Asked Questions
Does this comparison confirm vehicle fitment?
No. It performs a dimensional comparison of 245/60R18 and 255/55R19, not a complete vehicle fitment analysis.
Confirmed fitment still needs model year, trim, factory tire specification, wheel width, offset, bolt pattern, hub bore, brake clearance, suspension and fender clearance, plus load and speed-rating requirements.
What this tool can quantify from size (and published catalog fields when present): diameter difference (+1.58%), width difference (+10 mm), and wheel diameter requirement (18" → 19").
No approved rim-width range is listed for either size in this dataset, so rim fit must be confirmed from the specific tire maker’s documentation.
Load index and speed rating are not populated for both sizes in this dataset.
A diameter change within ±3% is only a common screening guideline — not a fitment guarantee for any specific vehicle.
How accurate are the comparison results?
Nominal tire dimensions for 245/60R18 and 255/55R19 are calculated from the tire-size code using standard geometric relationships, so the arithmetic for those nominal values is exact.
Real mounted tires can still differ because of tread design, approved measuring rim, inflation, load, remaining tread depth and casing construction.
For this pair, overall diameter moves +1.58% (29.57" → 30.04") and section width moves +10 mm (+4.08%).
This comparison is running on nominal size-code calculations for both 245/60R18 and 255/55R19. Prefer manufacturer-published overall diameter and revs/mile when you have selected a specific tire model.
Speedometer and gearing figures are theoretical: they assume the indicated speed is based on the original rolling circumference with no cluster recalibration.
How are tire dimensions calculated?
For metric sizes, sidewall height equals section width × (aspect ratio ÷ 100), wheel diameter is converted with 1 in = 25.4 mm, and overall diameter equals wheel diameter plus two sidewalls.
Circumference is π × overall diameter, and revolutions per mile equal inches per mile divided by that circumference.
Applied here: 245/60R18 uses 245 mm width and aspect ratio 60 on a 18" wheel → 5.79" sidewall and 29.57" overall diameter; 255/55R19 works out to 5.52" sidewall and 30.04" overall diameter.
The width code is nominal section width, not tread width, and the aspect ratio is a percentage of that section width.
Will the speedometer be affected?
Yes — the larger rolling circumference on 255/55R19 travels farther per wheel revolution, so at a given indicated speed the vehicle typically moves slightly faster than the cluster shows.
Circumference changes +1.47" (+1.58%), which is the same percentage order as the diameter change for this geometric model.
At an indicated 60 mph, the theoretical road speed is approximately 61.0 mph (+1.58% versus 245/60R18).
Actual cluster behaviour can still differ after tire wear, load, temperature or any OEM speedometer calibration.
Do I need new wheels?
Yes for bead-seat diameter: 245/60R18 is an R18 tire and 255/55R19 is an R19 tire (+1" wheel change). An R18 tire will not correctly seat on an R19 wheel.
Plan a 19" wheel with appropriate width for 255 mm section width, then confirm offset, bolt pattern, hub bore, brake clearance and load rating on the target vehicle.
No approved rim-width range is listed for either size in this dataset, so rim fit must be confirmed from the specific tire maker’s documentation.
Can different tire sizes use the same wheel?
Only when wheel diameter matches, the rim width sits in the approved range for both tires, load and speed requirements are met, and the bead-seat type is compatible.
245/60R18 (R18) and 255/55R19 (R19) cannot use the same wheel diameter; an R18 tire and an R19 tire do not share a bead seat.
A wider tire does not automatically require a wider wheel, but mounting outside the published rim range can distort the tread profile and change handling and load behaviour.
No approved rim-width range is listed for either size in this dataset, so rim fit must be confirmed from the specific tire maker’s documentation.
How much clearance should I check?
Clearance must be checked through the suspension and steering travel, not only when the vehicle is parked on level ground.
Inspect full steering lock, suspension compression, inner sidewall to strut or control arm, outer shoulder to fender or liner, brake and wheel-barrel clearance, and tire growth/deflection under load — plus any wheel offset or width change.
For this pair, half the overall diameter change approximates the static radius or ground-clearance shift: about +0.23 in from the +1.58% diameter move (29.57" → 30.04").
Width change (+10 mm) spreads around the wheel centreline only when wheel width and offset stay unchanged; a different offset moves the whole package inward or outward.
Can I mix tire sizes front and rear?
Only when the vehicle manufacturer approves a staggered or mixed setup — do not create one casually from a comparison tool.
Mixing 245/60R18 and 255/55R19 across axles would put roughly +1.58% (+0.47") of rolling-circumference difference between front and rear if one size sat on one axle and the other on the opposite axle.
ABS, stability control and especially AWD/4WD systems can be sensitive to axle circumference mismatch; transfer-case and differential hardware may see extra stress, and tire rotation patterns become limited.
Follow the placard or OEM staggered specification. There is no universal “safe” percentage that applies to every drivetrain.
Why do actual tire dimensions differ between brands?
Two products sharing the 245/60R18 or 255/55R19 size code can still publish different overall diameters and revolutions per mile.
Measuring rim width, tread pattern, sidewall and casing construction, rated load and pressure, manufacturing tolerances, and new-versus-worn tread all shift the measured envelope.
Use the size-code geometry on this page for planning, then prefer the manufacturer’s published diameter and revs/mi for the exact model you intend to buy.
What is the difference between nominal and published tire dimensions?
Nominal values come from the tire-size formula applied to the size code — for example 29.57" overall diameter on 245/60R18 and 30.04" on 255/55R19.
Published values come from physical measurement or manufacturer specifications for a specific brand and model, and can differ from that formula result.
Nominal figures are useful for generic size-to-size comparison; published figures are preferred for exact model-to-model analysis.
This comparison is running on nominal size-code calculations for both 245/60R18 and 255/55R19. Prefer manufacturer-published overall diameter and revs/mile when you have selected a specific tire model.
How does tire size affect effective gearing?
A larger rolling diameter on 255/55R19 produces taller effective gearing: fewer wheel revolutions per road mile and usually a small drop in engine RPM at a given true road speed.
revs/mi moves −11 (-1.56%). At 60 mph indicated, theoretical engine speed shifts with that circumference change — exact RPM also depends on final-drive ratio and transmission gear.
Acceleration response can feel slightly softer with taller gearing or sharper with shorter gearing; treat those effects as directional rather than certain for every powertrain.
Why does sidewall height matter?
Sidewall height sets how much vertical rubber is available to deflect under load.
For this pair sidewall changes −0.27" (5.79" → 5.52", -4.59%). Lower sidewalls generally reduce flex; taller sidewalls generally add compliance.
Construction, inflation pressure, load and tread design still matter — sidewall height alone does not determine handling or comfort.
- Calculated by TireReference (Tire Reference)
- Report a calculation issue
- Calculator logic updated: July 2026