Tires are the single biggest performance change you can make to a Mini-Z — bigger than motors, bearings, or springs. The right tires make a stock car fast and easy to drive; the wrong ones can't be tuned out. Two things decide a Mini-Z tire: compound (how soft the rubber is) and width (how much rubber meets the track). This guide maps both to the surface you actually run on, and follows the practice of Japanese RCP racers, where Mini-Z racing is most developed.
Reading Kyosho's numbers
Mini-Z tires are graded by degree — 20°, 30°, 40° and up. Lower number = softer = more grip, but more wear and heat. Higher number = harder = less grip, but more durable and freer-rotating on high-grip tracks. The same scale shows up as "Shore 20 / 30 / 40" on some packaging. Kyosho's main racing tires are the Racing Radial (narrow, MZW37) and Racing Radial Wide (MZW38), plus low-height slicks (MZW40) and high-grip compounds (MZW2). A radial generally grips more than a plain slick because the pattern edges bite into the surface.
The one rule: balance front against rear
On a rear-drive Mini-Z you tune grip front-to-rear by feel:
- Car pushes / won't turn in (understeer): add front grip with a softer front, or take grip off the rear with a harder or narrower rear.
- Car is loose / spins out (oversteer): add rear grip — soften the rear (a lower-degree compound), or fit a wider rear. You can also take a little grip off the front with a harder front.
If you only change one tire, change the rear. Rear grip has the biggest effect on how a Mini-Z drives — it's the standard "replace the rear first" advice from Japanese RCP racers.
Starting points by track surface
These are common starting points, not hard rules — local grip, temperature and how polished the track is all move the numbers. One Mini-Z quirk worth knowing: on a gripped-up urethane track, going softer than the baseline often loses grip rather than gaining it, so step harder (not softer) as a urethane track rubbers in.
| Surface | Front (8.5 mm narrow) | Rear (11 mm wide) | Notes |
|---|---|---|---|
| RCP / urethane (Kyosho's modular plastic track — the club-racing standard), normal grip | 30° low-height slick | 30° racing radial | The standard baseline — JP racers run 30 front / 30 rear. Softer than 30 often loses grip here. |
| RCP, gripped-up / hot (well-used, rubber laid down) | 30–40° | 30–40° | Step harder as grip rises, or the tire overheats and rotation goes lazy. |
| RCP, low grip (new, dusty or cold) | 30° | 20° | Drop the rear to a soft 20° for bite, and wipe the tires often. |
| Carpet (incl. punch carpet) | stock / 30° low-height | 20° soft (radial or high-grip) | Carpet standard is a soft 20° rear; the front can stay stock and move to 30° low-height as it wears. Aftermarket carpet tires go softer still. |
| Painted concrete / wood / asphalt (outdoor or high-abrasion) | 30–40° | 30–40° | Abrasive and high-grip: go harder or soft rubber shreds and can roll. Watch wear. (Less common than indoor RCP / carpet.) |
| Drift (PCB, tile, smooth floors) | hard drift tire | hard drift tire (Kyosho MDT001 8.5 mm / MDT002 11 mm) | Low-grip drift compound — a different goal from grip racing. |
What you can actually buy right now
The current standard is the 30° wide radial rear (MZW38-30) with a 30° low-height slick front (MZW40-30) — both readily available. The softer 20° wide radial (MZW38-20) is the go-to when you need more bite (low-grip tracks, carpet), but it has gotten scarce — it is marked discontinued at Kyosho America, though Japanese shops often still carry it. When you want a rear softer than Kyosho stocks, aftermarket brands — PN Racing, Atomic, GL Racing — fill the gap, especially for carpet.
Kyosho option tire part numbers
Kyosho currently lists six option-tire lines, each spanning some part of the 10°/20°/30°/40° degree range described above — the same rule applies here: lower degree stays softer and grippier, higher degree stays harder and more durable, so pick a row by tire type/width first, then move up or down the degree columns to tune grip. Not every line covers every degree; a — means Kyosho doesn't catalog a part number at that degree for that tire.
| Tire (Kyosho line) | 10° | 20° | 30° | 40° |
|---|---|---|---|---|
| High Grip (MZW2) | — | MZW2-20B | MZW2-30 | MZW2-40 |
| Super Low-Height Slick (MZW40) | — | MZW40-20B | MZW40-30 | MZW40-40 |
| Wide High Grip (MZW17, rear wide) | — | MZW17-20B | MZW17-30 | — |
| Racing Wide (MZW38, MR-04, rear wide) | MZW38-10 | MZW38-20B | MZW38-30 | MZW38-40 |
| Racing Radial (MZW37) | — | MZW37-20B | MZW37-30 | MZW37-40 |
| Low-Height Slick (MZW39, small-diameter narrow) | — | MZW39-20B | MZW39-30 | MZW39-40 |
A few usage notes straight from Kyosho's catalog: the Super Low-Height Slick (MZW40) mounts with double-sided tape rather than a standard bead fit, so budget for tape when you order a set. MZW17 (Wide High Grip) and MZW38 (Racing Wide) are both rear-wide-specific tires — don't fit either as a front. MZW38 is the current Racing Wide line built around the MR-04 chassis, and it's also the only line with a 10° option, for when even a 20° isn't enough bite. MZW39 (Low-Height Slick) is a small-diameter narrow tire — a smaller diameter than the standard 8.5 mm narrow front described above — so check fitment before swapping it in.
Width and height
A wider rear (11 mm) puts down more drive and corner-exit grip; go too wide and you invite body rub or lazy rotation. The front is almost always 8.5 mm narrow. Some narrow-body cars run an 8.5 mm rear too, trading grip for a tighter, more scale look. Low-height front tires drop the nose and quicken the steering; taller tires raise ride height and slow it a touch.
Keep tires clean — dust and oil off the track quietly kill grip. A quick wipe between runs is the cheapest grip you will ever find.
Related: Mini-Z wheels, offset & play · Mini-Z Wheel Offset Calculator · MR-03 vs MR-04.
