What are the first upgrades I should buy for a Mini-Z MR-03 ReadySet?

In order of priority: tires (Kyosho Radial Wide 20 degree rear and Low Height Slick 30 degree front with tire tape), then ball bearings to replace the stock plastic bushings, then a carbon or fiberglass T-plate. These three upgrades total under $50 and transform the car's grip and consistency.

Do I need to upgrade the bearings on an MR-03 ReadySet?

Yes. ReadySet cars ship with white plastic bushings in the wheels instead of ball bearings. The bushings create friction and wear out quickly, making the car slow and unpredictable. A standard 7-piece bearing set is a high-priority upgrade for any ReadySet.

What is the kingpin flip mod and does it cost anything?

The kingpin flip is a free handling mod on the stock MR-03. You disassemble the front knuckles and flip the kingpin pins upside down so the C-clip groove is at the bottom. This increases front suspension droop so the front tires stay in contact with the surface during hard cornering. It takes about 10 minutes and costs nothing.

What T-plate stiffness should I buy for an MR-03 ReadySet?

Start with Medium stiffness for most conditions. Medium gives the rear pod predictable flex for consistent corner exit. Softer T-plates suit very high-grip surfaces or drivers who want more rotation; stiffer T-plates suit lower-grip tracks. Medium is the safe starting point.

beginner

MR-03 ReadySet: First Upgrades Shopping List

The exact parts to buy first for a Kyosho Mini-Z MR-03 ReadySet: tires, bearings, T-plate, and the free kingpin flip mod. Under $50 total with Amazon links.

MR-03

You just bought a Mini-Z MR-03 ReadySet (RTR). You hit the track, and… it’s all over the place. It spins out, it wanders on the straights, and it feels “loose.”

You don’t need a $300 chassis upgrade. You need to fix the friction and the grip. Here is the exact shopping list to transform a stock MR-03 for under $50.

Still deciding between the MR-03 and MR-04? The MR-03 vs MR-04 Buyer Guide breaks down the differences before you buy.

Kyosho MR-03 EVO chassis top-down — the platform you're about to transform for under $50

1. Tires & Tape (~$18)

Priority: Critical The stock tires are hard rubber designed for shelf life, not grip. They are useless on RCP foam or carpet. Do not pass go. Buy these immediately.

Rear: → Kyosho Radial Wide 20° on Amazon (Grip)
Front: → Kyosho Low Height Slick 30° on Amazon (Steering)
Essential: → Kyosho Tire Tape on Amazon (Required to keep them on)

Note: If you have an MR-03 EVO chassis set, skip to step 3. You likely already have bearings. Not sure which compound to choose? Read our full Tire Compound Guide.

2. Ball Bearings (~$15)

Priority: High (ReadySet Only) Kyosho ReadySets come with white plastic bushings in the wheels. These create drag and wear out quickly, making the car slow and sloppy. A standard bearing set replaces these plastic rings with smooth steel ball bearings.

Result: Longer runtimes, higher top speed, smoother cornering.
Buy: → Kyosho Mini-Z Bearing Set on Amazon (or any 7-piece MR-03 set).

3. Carbon/Fiberglass T-Plate (~$12)

Priority: Medium The T-Plate is the rear suspension of the Mini-Z. The stock plastic one is soft and eventually snaps. A carbon or fiberglass T-Plate (usually “Medium” or “Soft”) gives the rear pod consistent flex, which means more predictable grip coming out of corners.

Buy: → Kyosho Carbon T-Plate Set on Amazon or PN Racing #4.
Learn More: See how T-Plates fit into the bigger picture in our MR-03 Platform Guide.

4. Kingpin Flip (Free!)

Priority: Handling Hack The front suspension kingpins on a stock MR-03 limit suspension travel (droop). The Mod: Take the front knuckles apart. Take the kingpin (the metal shaft) and flip it upside down so the C-clip groove is at the bottom. This effectively increases front suspension droop, helping the front tires stay on the ground during hard cornering.

Cost: $0.
Time: 10 minutes.

The $50 Summary

Upgrade	Part	Est. Cost
1. Grip	F/R Tires + Tape	$18.00
2. Speed	Ball Bearings	$15.00
3. Handling	T-Plate (Med)	$12.00
4. Hack	Kingpin Flip	$0.00
Total		~$45.00

If you have $5 left over? Buy a spare set of Wheel Nuts (you will lose one eventually).

Once these are sorted, the MR-03 Platform Guide covers the full competitive build path — brushless, ball diff, and suspension tuning. Want to go deeper on T-plate selection? See the T-Plate Setup guide. Considering ceramic bearings over the steel set? The Bearing Upgrades: Ceramic vs Steel guide breaks down where the extra cost pays off. When the stock motor and board start feeling like the ceiling (which they will if you’re racing regularly), do the FET swap before a full brushless conversion. It’s worth doing before you tune spring rates or ESC settings: the power response difference is real, and it costs about $15. And if you want the same under-$50 framework for every platform (not just MR-03), see the Best Budget Setups Under $50 guide.

Product images courtesy of Kyosho.