CTY2 & 72V: Tire Sizes and Fitment

This post provides a structured reference for building and upgrading 72V ONYX wheels.

It covers:

• Spoke patterns and their mechanical impact
• Stock RCR and CTY2 rim and tire dimensions
• Aftermarket rims and spoke sizing specifications
• Rim width, tire width, and dropout width relationships
• Required tools for wheel assembly and truing
• Tire sizing, fitment limits, and clearance constraints
• Tire selection for daily use and performance riding
• Advanced setup considerations for high-power builds

As power levels, weight, and riding demands increase, wheel and tire configuration becomes a critical factor in reliability, stability, and overall performance.

Simple Overview

If you just want the safe, proven setup:

• Spokes: Cross-laced (3-cross or 4-cross)
• Stock RCR/CTY2 rims: 17 × 1.60" front and rear
• Stock RCR/CTY2 tires: 3.00-17 front and rear
• Aftermarket rims: Width depends on tire, motor, dropout width, and swingarm configuration
• Daily tire: Michelin City Extra 2.75 × 17
• Performance tire: Michelin Pilot Street 2 (90/80 front, 100/80 rear)
• Pressure: 32 PSI front and rear

Everything below explains why these work best.

Spoke Patterns (Cross vs Radial)

Rims (17" and 18")

Spokes - Front (17" wheel)

Tire Fitment Basics

Stock RCR and CTY2 setup

• Front rim: 17 × 1.60"
• Rear rim: 17 × 1.60"
• Front tire: 3.00-17
• Rear tire: 3.00-17
• ~3.0" tire width
• ~3.0" sidewall height
• ~23" total diameter

Clearance limits (stock swingarm)

• Front: ~3.5" wide, ~2.8" sidewall
• Rear: ~3.9" wide, ~3.1" sidewall

Wider tires may require:

• Taller fork stabilizer
• Extended swingarm

These limits are based on real-world fitment and account for flex under load, not just static clearance.

Actual fitment depends on the tire model, mounted width, rim width, wheel centering, and tire construction. Tire sizes in the following tables are fitment references rather than universal guarantees.

Tire Fitment Reference (Stock Geometry)

Front Tire Fitment

Rear Tire Fitment (Stock Swingarm)

Fitment Notes

• Taller fork stabilizer may be required for larger front tires
• Rear fitment depends on true mounted width, not labeled size
• Rim width changes the mounted profile and width of the tire
• Knobby and dual-sport tires (Shinko 244, etc.) run larger than street tires
• Tread blocks can create clearance issues even when nominal tire width appears acceptable
• Verify chain clearance and wheel centering
• Always verify clearance under full suspension compression

For an 80/90-17 front and 110/80-17 rear combination on the stock 17 × 1.60" wheels, the 80/90-17 front is within the fitment range covered here. The 110/80-17 rear is different: it may be physically mountable on the 1.60" rim, but I would not describe it as a normally recommended rim-and-tire combination. Around 100/80-17 is the largest rear metric size I would recommend here without treating the setup as experimental fitment.

Tire Size Systems

Two formats:

• Inch sizing (3.0")
• Metric sizing (90/80)

Metric reference:

Example:

90/80 = 3.5" wide × 2.8" sidewall

These are nominal dimensions. Actual mounted tire dimensions can vary by tire design and rim width.

Tire sizing directly affects:

• Overall diameter
• Acceleration vs top speed
• Clearance at fork and swingarm
• Motor load and efficiency

Tire Load and Speed Index Explained

Tires include load and speed ratings that define safe operating limits.

Speed Rating

• P = 93 mph
• R = 106 mph
• S = 112 mph

The speed rating defines the tire’s ability to handle heat and structural stress at sustained speeds.

High-power ONYX builds should use:

R or S rated tires minimum

Load Rating

Load index defines how much weight a single tire can safely support.

Examples:

• 46 = 375 lb
• 50 = 419 lb
• 52 = 441 lb
• 57 = 507 lb

Load rating directly impacts:

• Sidewall stability
• Heat buildup under load
• Resistance to deformation

Heavier riders, passengers, or upgraded battery setups benefit from higher load ratings.

Common Tire Models (Comparison)

Weight, load index, and speed rating vary by exact tire size. Values above reflect common ONYX fitment sizes.

Tire Types by Use

These categories reflect real-world tradeoffs:

• Daily tires prioritize longevity and wet grip
• Performance tires prioritize traction and handling
• Mixed-use tires balance road and off-road capability

Always follow sidewall PSI limits during mounting.

Reference

For tire specs, comparisons, and purchase options:

• 72V ONYX Tires

Two Tires That Matter Most

Michelin City Extra

• Long tread life
• Strong wet grip
• Puncture resistant
• +10% longer lifespan vs City Pro
• +24% improved wet grip
• Water siping improves rain performance

Recommended sizes:

• 2.75 × 17 (best balance)
• 3.0 × 17 (mostly aesthetic increase)

Michelin Pilot Street 2

Performance setup.

Front:

• 90/80 × 17
• 112 mph rating
• ~3.5" width fits front without rubbing

Rear:

• 100/80 × 17
• 106 mph rating
• ~3.9" width fits rear swingarm perfectly

Characteristics:

• Closest feel to slick-style grip
• Significantly improved cornering confidence
• Higher grip results in faster wear

Recommended pressure:

• 32 PSI

Tire Diameter vs Acceleration

Tire diameter directly affects motor RPM required to maintain speed. Smaller diameters increase acceleration and torque at the wheel, while larger diameters reduce RPM and favor higher top speed.

Key Behavior

• Smaller diameter -> higher RPM -> stronger acceleration
• Larger diameter -> lower RPM -> higher potential top speed
• Increased diameter adds motor load and reduces effective torque

Reference

For additional context and updates:

• ONYX Tire Diameter RPM

Tubes and Flats

Best practices:

• 2-3mm thick tubes
• No slime
• No tire liners
• Use rim protectors

Slime can introduce imbalance and moisture-related corrosion. Tire liners can shift and create uneven wear.

Tube Compatibility

Use thicker tubes (3mm) for puncture resistance in daily riding. Use 2mm tubes for easier installation and lighter setups.

17" Tubes

18" Tubes

Rear Axle Torque (Quick Reference)

• Axle nut: 24mm
• Torque: 80 Nm
• Brake caliper bolts: 12 Nm
• Clean axle before install
• 1-2 drops threadlocker

Advanced Clearance Notes

• Shinko 244 (3.0") requires taller fork stabilizer
• 4" is the widest rear tire I have personally used on the 72V RCR without additional modifications
• Rear tires over 4.0" should be treated as modified fitment and may require extended swingarm plates
• Metric sizes above 100/80 may interfere with front clearance
• 110/80-17 rear tires on a stock 1.60" rim should be treated as experimental fitment unless the specific tire manufacturer approves that rim width; physical mounting does not guarantee correct profile or bike clearance
• Actual mounted tire width varies by tire design and rim width
• Chain, sidewall, tread, wheel centering, and suspension-travel clearance must all be checked

Clearance should always be verified under compression, not just static fitment.

Final Recommendations

• Zero drama: Michelin City Extra
• Maximum grip: Michelin Pilot Street 2
• Mixed use: Shinko 244
• Budget: ContiStreet

For wider rear-wheel builds, choose the tire first. Determine the tire manufacturer’s acceptable rim-width range, select the appropriate rim, and then verify the complete mounted wheel and tire assembly on the bike.

Tires outside that recommended rim-width range may still physically mount and have been used successfully in some configurations, including wider tires I have personally run on 1.60" rims. Treat those setups as experimental rather than recommended fitment and verify the inflated tire profile and all bike clearances before riding.

Do not select a rim solely by trying to maximize rim width. The correct combination depends on the tire, actual mounted dimensions, motor and dropout width, wheel centering, chain clearance, and swingarm configuration.

Wheel setup affects:

• Acceleration
• Top speed
• Motor load
• Braking
• Stability
• Range

It is one of the highest-impact upgrades you can make on an ONYX.

Detailed Guides

• QS205 Spoke Sizes, Rim Sizes, and Wheel Lacing for ONYX RCR 72V

• 72V: Rim Width and Swingarm Clearance