OEM Safe
Out of spec
Beyond OEM tolerance — speedometer and ABS need professional review.
Fitment comparison
245/45 R20versus225/45 R17
Δ Ø -94.2 mmSpeedo -12.93%Aggressive
225/45 R17 is shorter than 245/45 R20 — quicker gearing feel, tighter arch gap, livelier throttle response.
225/45 R17 drops the rim from 20 to 17 inches versus 245/45 R20, trading wheel size for taller sidewall. This alternative fitment noticeably changes overall diameter compared to OEM. The dashboard speed will be significantly off — plan on recalibration before daily use. The narrower section trims rolling resistance and tends to cut through snow more effectively. A diameter change beyond 5% is aggressive enough to influence ABS, traction control and gearing; treat it as a serious modification.
TakeTreat as a serious modification — verify clearance, recalibrate the speedometer and reassess load capacity.
Quick fitment verdict
245/45 R20 → 225/45 R17 at a glance
Fender Clearance
Clears fender
Width and diameter stay close to stock — arch clearance unchanged.
Speedometer Impact
-12.93%
Dash reads 87.1 km/h at a true 100 km/h — recalibrate.
Daily Driving
Aggressive
Geometry deviates enough to matter — confirm clearance before daily use.
Side-by-side telemetry
Dimensional read-out
Current
245/45 R20
- Diameter
- 728.5 mm
- Sidewall
- 110.3 mm
- Wheel
- 20″
- Width
- 245 mm
Δ delta
Ø -94.2 mm
SW -9.0 mm
RH -47.1 mm
NewNew
225/45 R17
- Diameter
- 634.3 mm
- Sidewall
- 101.3 mm
- Wheel
- 17″
- Width
- 225 mm
Real-world effects
How this swap actually feels
- Steering response75/100 · Sharper turn-in
- Ride comfort45/100 · Firmer ride
- Fuel economy18/100 · Slightly lower drag
- Highway cruising4/100 · Higher cruise revs
- Pothole resistance39/100 · Less wheel protection
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Ride height
Lower stance
Chassis drops — tighter arch gap, more aggressive stance.
New tire drops ride height by ~47.1 mm — tighter arch gap, lower stance.
Suspension travel · arch clearance
Wheel gap
Wheel sits closer to the fender
How the arch-to-tire gap reads from across the parking lot — the visual stance change everyone notices first.
245/45 R20
225/45 R17
Wheel-gap Δ-47.1 mm
Static · unloaded chassis
Fender relationship
Tucked · Flush · Poke
The visual relationship between the tire's outer edge and the fender lip — the lens enthusiasts use to judge a fitment.
Tucked
Inside fender
Flush
Lip-aligned
Poke
Outside fender
Width & offset dependent
Speedometer reality
Dash reads 87.1 km/h
Shorter rubber: dashboard reads conservatively low — you're slower than it claims.
ABS · ESP · cruise control
Setup telemetry
How this setup changes the car
Driver-perspective read-out of the 245/45 R20 → 225/45 R17 swap — steering, comfort, stance and dash behavior in plain enthusiast language.
Steering feel
-9.0 mm sidewallSharper steering response
Shorter sidewall transmits inputs faster — quicker turn-in, more confident on-center feel.
Ride firmness
45% → 45%Slightly firmer over rough pavement
Expect more chatter on broken tarmac and a sharper pothole strike — keep an eye on wheel damage risk.
Fender relationship
-20 mm widthMore tuck under the arch
Narrower contact patch tucks slightly inboard — cleaner look from the rear three-quarter.
Speedometer behavior
-12.93%Out of tolerance — recalibrate
Beyond ±5% — speedometer, gearing and ABS calibration all need a professional review.
Daily drivability
Ø -94.2 mmAggressive setup — verify before daily use
Geometry deviates enough to matter — check clearance, recalibrate the dash, then re-evaluate.
Direct answer
Is 225/45 R17 OEM-safe?
No. Overall diameter changes by -12.93% versus 245/45 R20. Not OEM-safe. Overall diameter strays beyond ±5% — recalibration and clearance review are required.
Direct answer
Will 225/45 R17 rub?
Borderline. Width changes by -20 mm and diameter by -94.2 mm. Borderline — check fender lip and inner strut clearance under load.
Direct answer
Does the speedometer change?
Yes — by -12.93%. Swapping 245/45 R20 for 225/45 R17 changes overall diameter, so at an indicated 100 km/h your true speed becomes 87.1 km/h. That's outside safe tolerance — recalibrate.
Direct answer
Does lower sidewall affect comfort?
Yes — firmer ride. Sidewall changes by -9.0 mm (45% → 45%). Ride becomes firmer and steering sharper, but potholes and expansion joints hit harder and wheel damage risk rises.
Current Tire
245/45R20
New Tire
225/45R17
Fitment · Scaled comparison
● Not recommended
245/45 R20
Diameter
-94.2 mm
-12.93%
Sidewall
-9.0 mm
Speedometer
87.1 km/h
at true 100
Clearance
Not recommended
225/45 R17
Ground line · Scaled comparison
Not Recommended
Over 5% — speedometer & ABS may misread
Diameter change
-94.2 mm
-12.93%
Speedometer at 100
87.1 km/h
-12.93% error
Ground clearance
-47.1 mm
ride height delta
Sidewall change
-9.0 mm
revs/km: 501.8
Permalink for this comparison:
/compare/245-45-r20-vs-225-45-r17Detailed comparison
| Metric | 245/45 R20 | 225/45 R17 | Difference |
|---|---|---|---|
| Overall diameter | 728.5 mm | 634.3 mm | -94.2 mm (-12.93%) |
| Sidewall height | 110.3 mm | 101.3 mm | -9.0 mm |
| Circumference | 2.289 m | 1.993 m | -295.9 mm |
| Revs / km | 436.9 | 501.8 | +64.9 |
| Ground clearance | reference | -47.1 mm | -47.1 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 87.1 km/h | -12.93 km/h |
Verdict: danger
Over 5% diameter difference — likely to affect speedometer accuracy, ABS calibration and gearing. Not recommended without professional review.
Dimensional comparison
Side-by-sideScaled engineering side-profile of both tires. Width, sidewall and overall diameter are dimensioned so you can see the change at a glance — without parsing the numbers.
Current
245/45 R20- Profile
- 45%
- Circumference
- 2.289 m
New
225/45 R17- Profile
- 45%
- Circumference
- 1.993 m
Side-by-side fitment
GeometryCurrent
245/45 R20- Section width
- 245 mm
- Aspect ratio
- 45%
- Sidewall
- 110.3 mm
- Wheel diameter
- 20″(508 mm)
- Overall diameter
- 728.5 mm(28.68″)
- Circumference
- 2.289 m
- Revs / km
- 436.9
New
225/45 R17- Section width
- 225 mm
- Aspect ratio
- 45%
- Sidewall
- 101.3 mm
- Wheel diameter
- 17″(432 mm)
- Overall diameter
- 634.3 mm(24.97″)
- Circumference
- 1.993 m
- Revs / km
- 501.8
Real-world consequences
Pros / consNarrower tire (-20 mm)
Section width- Better aquaplaning resistance
- Lower rolling resistance and slightly better MPG
- Quieter ride, less tramlining
- Lighter unsprung mass on the corner
- Less dry grip at the limit
- Smaller contact patch under hard braking
- Stance can look tucked or undersized
Shorter overall (-94.2 mm)
Rolling diameter- Shorter effective gearing — perkier acceleration
- Lower center of gravity, sharper transitions
- More fender and arch clearance
- Speedometer reads high by ~12.9%
- Engine spins higher at cruise, small MPG hit
- ABS / ESP recalibration may be advisable
-3″ rim downsize
Wheel diameter- Cheaper winter / track tire sizing
- Lighter overall package, less unsprung mass
- More sidewall = more impact absorption
- Less aggressive stance
- Possible brake caliper clearance issue going too small
How it changes driving feel
Seat-of-the-pantsSteering response
Softer, slower
Ride comfort
Comparable
Road noise
Similar cabin noise
Wet / aquaplaning
Comparable wet behavior
Fuel economy
Small MPG penalty likely
Curb / pothole protection
About the same
Fitment risk check
Verify before installSpeedometer drift
~12.9% diameter delta — speedo and ABS calibration likely affected.
ABS / ESP calibration
Outside factory tolerance — recalibration may be required for safety systems.
Reduced gearing range
Shorter rolling diameter raises cruise RPM and effective gearing.
Cluster preview
Excessive driftSpeedometer impact
At a true 100 km/h, your dashboard will read 87.1 km/h after switching to 225/45 R17 — a -12.93% offset. Use the speedometer error calculator for any indicated speed, and the speedometer error guide for the full background.
Ground clearance change
The new tire's half-diameter changes ride height by -47.1 mm. Small differences are absorbed by suspension travel, but anything beyond ±10 mm can affect headlight aim, fender clearance and bump-stop margin. See the plus-sizing guide before committing.
Back to
245/45 R20
Back to
225/45 R17
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