VehiclesArrma Granite MEGA 665

Arrma Granite MEGA 665

1/10 scale · monster truck · ARA4202V4

Final drive: 10.83:1
Tire: 128mm

Open in Top Speedsourced

Arrma Granite MEGA 665 — Photo: Horizon Hobby

Specifications

Last modified Sep 23, 2026

Spec	Value	Basis
Drivetrain
Pinion	15TStock	Stock
Spur	57TStock	Stock
Transmission & axle	2.85:1Stock	Stock
Spur ÷ pinion	3.800:1Calculated	Calculated
Final drive	10.83:1Stock	Stock
Wheels & tires
Tire diameter	128mmStock	Stock
Rollout	37.1mm per motor turnCalculated	Calculated
Power
Motor	Not applicable
Motor shaft	Not published
Battery	Up to 2SLiPoStock	Stock
Performance
Theoretical top speed	Not applicable
Vehicle
Part number	ARA4202V4
Scale	1/10
Class	Monster truck

Stock is as the vehicle ships. Calculated is worked from the stock figures on this page rather than stored beside them, so the two cannot drift apart. Not applicable means the vehicle does not come with it, like the motor on a roller or the tires on a race kit, or does not have one, like a KV rating on a brushed motor. Not published means it exists but no source we could find prints it.

Gearing parts

Pinion and spur parts for the Arrma Granite MEGA 665: fitted, and optional gearing supplied in the box
Component	Teeth	Pitch	Bore	Part number
Fitted at the factory
Pinion	15T	Mod 0.8	3.175 mm	ARA311077 (opens in a new tab)
Spur	57T	Mod 0.8	Not applicable	ARA-1148 (opens in a new tab)

Tooth counts are the ones in the specifications above. Pitch is given as metric module (Mod 1, Mod 0.8) or diametral pitch (32P, 48P). They are different standards and are not interchangeable, even where the numbers look close. Bore is the pinion’s hole, listed separately from the motor shaft. Linked part numbers go to the maker's or official distributor's page for that part.

How these numbers were settled

The current brushed Granite 4X4, with an Arrma MEGA 665 13T high-torque brushed motor and a Spektrum 40A brushed 2-in-1 ESC and receiver; Horizon lists 2S LiPo compatibility.

Brushed, so there is no KV.
Horizon prints Pinion 15T, Spur Gear 57 and Internal Gear Ratio 2.85, and the standard-parts list names the 15T pinion, the 57T composite spur and the 37T diff sets with 13T input gears.
Final drive is 57/15 x 2.85 = 10.83.
The stock dBoots Fortress MT tire (ARA-1608) prints an overall diameter of 5.0 in (128mm).

Documents

ManualInstruction manual (Horizon PDF) (opens in a new tab)Pinion/spur mesh, PDF p. 17
Exploded viewExploded view (Horizon PDF) (opens in a new tab)15T STD pinion, motor and 57T spur
Parts listParts tech pack with 0.8 Mod pinion options (Horizon PDF) (opens in a new tab)Options, p. 2

Sources

Every figure on this page traces to one of these. Where they disagreed, the note above says which was used and why.