Dedicated Subsystem WorkbenchPlatform Gen: 2020–2024

2021 Harley Davidson Low Rider S (FXLRS Milwaukee-Eight) Tire Sizes, Cold Pressures & Gearing Ratios

OEM tire sizes, front cold PSI (), rear cold PSI (), sprocket teeth count, final drive ratio, and chain pitch for 2021 Harley Davidson Low Rider S (FXLRS Milwaukee-Eight).

Technical PassportOEM VERIFIED

Engine

1868cc

Cooling

Air/Oil-Cooled

Final Drive

Belt Drive

Engine Oil

4.70 L (5.00 US qt)

Spark Plug

Harley 6R10 / NGK CPR7EA-9

Front Tire

110/90B19

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Gen 2020–2024

Factory Platform Compatibility: All workshop fluid capacities, maintenance milestones, torque specifications, and consumables on this specification sheet are factory-identical across model years 2020 through 2024.

SPECS-TO-CART BUNDLESFactory Direct-Fit Maintenance Bundles Available

1-Click verified Motul engine oil service kits, race filters, spark plugs, and brake fluid pre-measured for this 2021 Harley Davidson Low Rider S (FXLRS Milwaukee-Eight).

Configure Service Bundles→

Select Model Year:(Active: 2021)
5 Production Years (2020–2024)

2020 2021 2022 2023 2024

Suggested Items3 Verified Workshop Consumables Available for this Job

View Suggested Items ↓

Tire Engineering & Multi-Scenario Pressure Matrix

ETRTO Validated

Inflation targets calibrated across operating modes, verified rim width ranges, and certified alternate sizes.

Shop Direct-Fit Tires

Multi-Scenario Inflation Pressures

Solo Street / CommutingCold Baseline

Front: 36 PSI

Rear: 40 PSI

Two-Up Passenger & LuggageMax Load

Front: 38 PSI

Rear: 42 PSI

Off-Highway / Terrain Pressure

Maintain OEM cold baseline for street transfers; adjust -2 to -4 PSI for loose terrain.

Rim Geometry & ETRTO Envelopes

Front Wheel

OEM Rim Width:3.50"

Permissible Envelope:3.50" - 3.75"

Rear Wheel

OEM Rim Width:5.50"

Permissible Envelope:5.50" - 6.00"

Operating outside ETRTO envelope width alters crown radius, accelerates shoulder wear, and impacts lean stability.

Factory Dimensions & Verified Alternates

Factory Standard Sizes

Front:110/90B19

Rear:180/70B16

Shop In-Stock Matched 2-Tire Sets→

Verified Alternate Fitments

Factory Standard

Alternate profiles verified for swingarm, chain guard, and fender clearances.

Final Drive Gearing & Speed/RPM Calculator

Belt Drive

Factory reduction ratios, interactive sprocket gearing simulator, 6th gear cruising RPM matrix, and swingarm chain adjustment tolerances.

Launch Full Gearing Simulator Shop Drive Belts

Drive Architecture

Poly-Chain Carbon Belt

OEM Pulleys

32T Transmission / 66T Wheel

OEM Final Ratio

2.063 : 1

Belt Teeth & Width

142T • 1.000 in (25.4 mm) Carbon Core

Cold Tension Deflection

1/4 - 5/16 in (6.4 - 7.9 mm) deflection with 10 lbs force

Quick Gearing Presets

Front Transmission PulleyStock: 32T

32 Teeth

Factory teeth count

Rear Wheel Belt PulleyStock: 66T

66 Teeth

Factory teeth count

Drive Ratio & Torque Impact

Calculated Final RatioStock: 2.063

2.063 : 1-0.02%

Drivetrain Torque Delta

0.0% Taller Gearing (Reduced Highway RPM)

Lengthens transmission gears, lowers sustained engine RPM on motorways, and reduces engine buzz and vibration.

Countershaft Speedo Variance:+0.0%

At 70.0 mph indicated speed, true vehicle ground speed is 70.0 mph.

Cruising Engine RPM in 6th Gear

60 MPH

Stock: 2,172 RPM

2,171 RPM

-1 RPM

70 MPH

Stock: 2,534 RPM

2,533 RPM

-1 RPM

80 MPH

Stock: 2,896 RPM

2,895 RPM

-1 RPM

Calculated using factory 6th gear ratio (1), primary reduction (1.353), and 180/70B16 rolling circumference.

Belt Tension & Deflection Spec

Cold Deflection Tolerance

1/4 - 5/16 in (6.4 - 7.9 mm) deflection with 10 lbs force

Check tension using a 10-lb belt tension gauge at the lower belt run midpoint window on the side stand.

Belt Architecture

142T • 1.000 in (25.4 mm) Carbon Core

Inspect poly-chain carbon teeth for stone cuts and check tension on side stand cold

Recommended Belt: Gates Poly Chain Carbon Drive Belt

Shop Belt Tension Gauges Find Direct-Fit Gearing Sets

Factory Chassis Geometry

Chassis Alignment, Drive Tension & Rear Axle Calibration

Precision workshop alignment tools, dynamic drive tension tolerances, and axle spindle calibration for the 2021 Harley Davidson Low Rider S (FXLRS Milwaukee-Eight).

Belt Drive Architecture

Secondary Belt Deflection & 10-lb Tension Calibration

FACTORY BELT DEFLECTION SPEC:

1/4 - 5/16 in (6.4 - 7.9 mm) deflection with 10 lbs force

Measure cold deflection with a spring-loaded belt tension tool applying exactly 10 lbs (4.5 kg) of upward force at the lower belt run inspection window on jiffy stand.

CARBON BELT TOOTH & FLANGE INSPECTION:

142T • 1.000 in (25.4 mm) Carbon Core

Inspect polyurethane cog teeth for stone gouges or embedded gravel. Verify rear pulley chrome flanges show even belt tracking without edge fraying.

Official NHTSA Safety Recalls & Technical Bulletins

0 Open Campaigns (Clean)

U.S. Department of Transportation compliance database (Title 49 U.S.C. Chapter 301).

Verify VIN on NHTSA.gov

No Active Federal Safety Recalls Reported

The U.S. DOT National Highway Traffic Safety Administration (NHTSA) records zero open safety recall campaigns for the 2021 Harley Davidson Low Rider S (FXLRS Milwaukee-Eight) platform. Always check your individual 17-digit VIN at an authorized dealership or via NHTSA.gov for individual recall completions.

OEM Workshop Archives

Official Factory Service Bulletins & Field Updates

4 Documented Bulletins

Bulletin #M1524M1524: RECALL 0177 - 2019 - 2021 SPORTSTER - HEADLAMP BULB SHIELD

Source: Harley_M1524_Recall0177.pdf

Mandated Torques:Torque: 5.8–6 in-lbs (0.66–0.68 N·m) (Bulb Shield Screw)Torque: 35–44 in-lbs (4–5 N·m) (Bracket to Visor Screws)Torque: 10–16 ft-lbs (13.5–21.6 N·m) (Visor Bracket Screws)

Consumable Specs:Loctite 243 Medium Strength Blue Threadlocker (HD Part # 99642-97)

Genuine Part Numbers:68297-05A9150010799642-97

Fastener Stack ArchitectureExploded View: Headlamp Visor Fastener & Vibration Stack (Bulletin M1524)

3-Stage Torque Map

Select any fastener or shield component to inspect exact torque specifications.

Component InspectorNHTSA Recall 0177 / M1524

Self-Tapping Shield Screw with Blue Loctite 243

Consumable: Loctite 243 (HD # 99642-97)

Factory Torque Specification

5.8–6.0 in-lbs (0.66–0.68 N·m) (CRITICAL LOW TORQUE)

Technical Assembly Note

MUST apply Loctite 243 Blue Threadlocker. Due to reuse of self-tapping screw into stamped bracket, STRICTLY do not exceed 6 in-lbs or threads will strip.

Vibration & Chemical Retention

Loctite 243 Medium Strength Blue Threadlocker (HD Part # 99642-97) mandatory on bulb shield screw to prevent thermal loosening.

Bulletin #M1568M1568: SAFETY RECALL 0635 - FRONT BRAKE LINE BANJO BOLT ASSEMBLY

Source: Harley_M1568_Recall0635.pdf

Mandated Torques:Torque: 19–21 ft-lbs (25.8–28.5 N·m) (Front Brake Line Banjo Bolts)

Consumable Specs:Harley-Davidson Platinum Label DOT 4 Brake Fluid

Genuine Part Numbers:2879401841751-06A41800770418007724180077341800774

Technical IllustrationExploded View: Hydraulic Brake Switch & Banjo Bolt Assembly

Official NHTSA PDF

Hover or Click Component to Inspect

Component SelectedOEM # 41747-06

Cross-Drilled Banjo Bolt

Cross-drilled hydraulic passage. Torque to exact factory range. Do NOT over-tighten or bolt can shear.

Torque Specification:19–21 ft-lbs (25.5–28.5 N·m)

Select Stack Layer:

Electrical Harness Schematic40-Pin BCM Electrical Harness Pinout & Wiring Map (Bulletin M1568 / Recall 0635)

40-Way Sealed Header • Cavity F3

Click Pin F3 or center keyway to inspect technical harness specifications

Inspection TargetRecall 0635 / M1568

BCM Terminal Cavity F3 (Recall Signal Input)

Jumper Terminal Wire # 69203239

Mechanical Engagement:Terminal Click-Lock Retention

MANDATORY RECALL PIN INSERTION. Insert jumper terminal into cavity F3 of the 40-way BCM harness connector until an audible click is heard. Tug lightly to verify positive secondary terminal engagement.

Interactive Circuit Nodes:

STEP 1: HARNESS CLICK VERIFICATIONSlide terminal wire 69203239 into Cavity F3 until secondary TPA wedge clicks flush. Perform gentle pull test.

STEP 2: CHASSIS GROUND TORQUEClean left-side frame ground stud. Fasten jumper ring terminal to 45–60 in-lbs (5.1–6.8 N·m).

STEP 3: DIGITAL TECHNICIAN II SYNCFlash BCM software to 28794018 YM0+. Depress rear brake pedal to trigger auto-stop calibration countdown.

Chassis Routing ArchitectureTrike Frame Jumper Wire Routing & EHCU Ground Map (Bulletin M1568 / Recall 0635)

Figures 5 & 6 • Behind EHCU

Click routing channel, ground stud, cable straps, or switch to view shop notes

Chassis Routing NodeRecall 0635 / M1568

Under-Tray Sub-Harness Route (Behind EHCU)

Recall Routing Path (Figure 6)

Mechanical Anchor:Protected Chassis Channel

MANDATORY ROUTING CLEARANCE. Route jumper harness # 69203239 behind the Electro-Hydraulic Control Unit (EHCU) assembly. Keep clear of hot exhaust pipes and moving suspension linkages.