Bought a beautiful AutoScale body — a Skyline, an NSX, a GT3 car — only to find the wheels sit too far in, poke out past the arches, or the shell won't sit down on the chassis? That is the most confusing part of the Mini-Z platform: you configure the chassis to match the body, not the other way around.
Two things control the fit. Wheelbase (the distance between the axles, set by your motor mount and rear pod) decides whether the body physically fits. Wheel offset (how far each wheel sits in or out, set by the wheels) decides whether it looks right and the tyres do not rub. Get the wheelbase right and the body fits; get the offset right and it sits right.
Wheelbase vs offset: the two things that matter
Keep these separate in your head and most fitment confusion disappears:
- Wheelbase — front-to-back axle distance, set by the motor mount and rear pod. If the shell will not sit down or the arches do not line up with the wheels, this is your problem.
- Offset — how far each wheel face sits out from the hub, in mm, set by which wheels you fit. If the wheels tuck inside the arches, or poke out and rub, this is your problem.
Wheelbase makes it fit; offset makes it look right.
Rear pod and motor mount: why the letters are confusing
Mini-Z mounts are labelled RM, MM, LM and HM — but the letters mix up two different things, and even the RC community does not agree on what some of them stand for. Do not trust the letters alone; check the wheelbase in mm and your body's spec sheet.
The letter describes one of two things:
- Where the motor sits front-to-back (this mainly sets wheelbase and balance):
- RM — "Rear Motor" (some say "Regular Mount"): motor behind the rear axle. Short wheelbases (86–94 mm). Most rear grip and the sharpest corner entry; rotates less and can understeer on power. Fits the most bodies.
- MM — "Mid Motor": motor ahead of the rear axle. Long wheelbases (98–106 mm). Balanced, rotates and exits corners well, the most stable — the beginner-friendly choice.
- How the motor is mounted for height (this mainly sets centre of gravity):
- LM — usually "Low Mount": a low centre of gravity for a fast, stable car, but only a few bodies fit. Note: Kyosho's own blog also uses "LM" for a long 102 mm mount, so this letter is genuinely ambiguous — always check the mm.
- HM — "High Mount": the motor sits on top of the axle to fit tall, short compact-car bodies. The high weight makes the car tip more easily.
- MM2 / MML — newer mid-mount variants that drop the motor lower for a lower centre of gravity at the same wheelbase.
Bottom line: the wheelbase in mm is the number that matters; the letter is just a hint.
Mini-Z wheelbase options
Kyosho sizes wheelbase with both a letter code and a millimetre figure, and every AutoScale body is labelled with the wheelbase it needs.
| Code | Wheelbase | Typical mount | Character |
|---|---|---|---|
| S | 86 mm | RM | Shortest — twitchy, hardest to drive |
| M | 90 mm | RM | Short, nimble |
| L | 94 mm | RM (also HM, MM2) | Common scale wheelbase |
| LL | 98 mm | MM (also MML, MM2) | Most stable — beginner-friendly |
| 3L | 102 mm | MM / LM (also MML, MM2) | Very stable, slower to rotate |
| 4L | 106 mm | MM (also MML) | Longest — niche |
How to read what a body needs (the part-number trick)
Kyosho prints the recommended chassis setup right in the AutoScale part number. Learn to read it and most of the guesswork disappears.
| In the part number | Means | Example |
|---|---|---|
| MR-03N | Narrow chassis (front/rear width under ~70 mm) | MR03N-RM |
| MR-03W | Wide chassis (over ~70 mm) | MR03W-RM |
| -RM / -MM / -LM | Recommended motor mount, which tells you the wheelbase | -RM ≈ 94 mm, -MM ≈ 98 mm |
| Offset line (F / R) | Recommended front and rear wheel offset | F: Narrow +1.5 / R: Wide −1.0 |
Example: ASC MR03N-RM Honda NSX means narrow chassis, rear-motor, 94 mm wheelbase. The listing's offset line (for example "F: Narrow +1.5 / R: Wide −1.0") tells you exactly which wheels to run.
The offset rule (and a calculator to do the maths)
Offset is measured in mm. A bigger or more-positive number pushes the wheel further OUT (wider); a negative number tucks it IN. Front and rear are set independently. Factory wheels come as narrow (8.5 mm wide) in offsets 0 / 1.0 / 1.5 / 2.0 / 2.5, and wide (11 mm) in offsets −1.0 / 0 / 1.0 / 2.0 / 3.0. Wide is about 5 mm wider overall — roughly 2.5 mm of offset per side.
Every AutoScale body lists a recommended width and offset. Add them to get a target total, and keep that total constant when you change wheel width: needed offset = target total − wheel width. For example, a 98 mm body spec'd at narrow (8.5) + offset 1.5 = 10.0 total; to run wide (11) rears, the offset = 10.0 − 11.0 = −1.0, so you fit "wide −1" wheels.
Use our Mini-Z Body Fitment and Offset Calculator → to work this out for the front and rear in one step.
Step by step: fitting an AutoScale body
- Read the body's spec — the part number plus the front/rear offset line. Note its wheelbase and offsets.
- Match the wheelbase first. Set your motor mount and rear pod to that wheelbase (for example 94 mm RM vs 98 mm MM). This decides whether the shell sits on the posts.
- Match narrow vs wide. If the body is wide and your chassis is narrow (or vice versa), swap the front upper and lower plates and the tie-rod, and use the matching rear pod width.
- Set the offset. Fit the wheels the body calls for. Unsure? Try +2.0 on the front first — it solves most MR-03 fit problems.
- Check for rub at full steering lock and full suspension compression before you run.
Wheels and offset: a durable, non-wobble fit
Wheels that wobble or crack usually come from one of two things: an offset that forces the tyre against the arch (constant rubbing stresses the rim), or cheap rims on a high-grip surface. Use the offset the body specifies rather than forcing a wider stance, seat the wheel fully on the hex, and step up to a sturdier rim if you race on high-grip carpet or PCB. One more gotcha: Mini-Z RWD and AWD wheels are not interchangeable — the hub geometry is different.
Deciding between chassis, or whether to upgrade what you have? See Mini-Z MR-03 vs MR-04: what''s different and how to upgrade.
Dialing in your wheels? See Mini-Z wheels: offset, play & a fit that won''t wobble or crack.
