33″ Wheels
For the first half of the 20th century, 33″ wheels were the workhorses of the North American freight fleet. They were fitted to cars rated between 50 and 70 tons (roughly 100,000–140,000 lb) and appeared under almost everything from boxcars to gondolas and flatcars.
From the early 1900s through to the 1950s, 33″ wheels offered a dependable compromise between strength, cost, and ride quality. They were first made from cast iron, then from better grades of steel as technology advanced. In service they did the job well enough, and they were cheap to replace when they wore out.
Today, 33″ wheels are mostly confined to lighter or older stock such as cabooses, maintenance vehicles, and preserved freight cars. They belong to an earlier era, when wagons were smaller, speeds were lower, and capacity was measured in simple tons rather than technical load ratings.
36″ Wheels
By the late 1950s, freight was getting heavier, trains were getting longer, and the railroads were trying to run faster without shaking everything to pieces. The answer came, in part, from bigger wheels. The 36″ wheel became standard for 100-ton cars (about 200,000 lb) and for anything expected to do serious work.
The larger diameter spreads the load, runs cooler, and gives better riding at speed. Modern hoppers, tanks, and flats almost all have 36″ wheels for that reason. Passenger stock also settled on 36″ long ago, finding that the larger wheel gave a smoother, steadier ride.
Modern wheels are precision-machined from heat-treated steel alloys and are expected to survive years of heavy use before they need reprofiling. They are tougher, quieter, and a world away from the crude cast wheels of a century ago.
Cabooses
Cabooses, those little offices on wheels, followed their own rules. Early ones, up to the 1950s, usually ran on 33″ wheels, matching contemporary freight cars. As the trains they followed became faster and heavier, some were fitted with 36″ wheels for a steadier ride.
Wheel size on cabooses often depended on the railway and the conditions they worked in. Mountain lines liked the extra steadiness of 36″ wheels on long grades, while others stuck with 33″ until the cabooses themselves disappeared from service. The mix tells the story of how the North American freight train evolved from small and simple to large and standardised.
N Scale Metal Wheelsets
From “Pizza Cutters” to Precision Wheels
N scale wheelsets have changed dramatically since the 1960s. Early Micro-Trains cars used one-piece plastic wheelsets with large flanges that earned the nickname “pizza cutters”. These ran well on code 80 track, with rails 0.080″ tall, but struck the spike heads on finer code 55 track, which more closely represents real rail height.
Micro-Trains later introduced shallow-flange plastic wheels that performed well on code 55. In the 1990s, many N scale cars from other manufacturers still suffered from poor wheel quality. Trucks often did not roll freely, wheels were out of round or mounted off-centre, and some cars would shimmy along the track or derail for no apparent reason. Replacement wheelsets were hard to find, and the problem often lay as much with the truck frames as with the wheels themselves. Many modellers simply replaced the entire trucks with Micro-Trains units, which transformed the running quality.
Micro-Trains’ own wheels were not perfect either, as they retained their oversized flanges for many years. The company later introduced a low-profile wheel option, and more recently a mid-sized flange has become standard, providing a practical balance between appearance and reliable running.
Plastic wheels still have their merits. Because the wheel and axle are moulded as one piece, they remain reliably in gauge. Being non-magnetic, they also avoid interference from uncoupling magnets. Their main drawback is that plastic is non-conductive, allowing static to build up and attract dust and fluff to the treads.
Metal wheels, by contrast, roll more freely and conduct away static. The light friction of metal on metal polishes both wheel and railhead, keeping them clean. They add a little weight too, which lowers a car’s centre of gravity and improves running. Tests show that four plastic wheelsets weigh about 0.57 g, while four metal wheelsets weigh around 2.5 g, roughly four times as much. The increase is small in absolute terms but can improve tracking slightly, especially on longer trains.
Shiny metal wheels benefit from a touch of finishing. On real railways, the wheel faces quickly oxidise to a dull brown while the treads stay bright through use. Painting or chemically darkening the wheel faces produces a far more convincing appearance.
The current market offers a wide range from manufacturers such as ScaleTrains (formerly Fox Valley Models), InterMountain, Tangent Scale Models, Atlas, Eastern Seaboard Models, BLMA and NorthWest Short Line. Modern N scale wheelsets are round, true, and closely match the proportions of the prototype.
Plastic or metal, the key is consistency and proper fit. Trying a few brands will usually reveal what works best for a given model. The improvement in running quality is immediate and often striking.
Why Wheel Size and Axle Length Matter
Early N scale metal wheels were crude compared with today’s standards, with thick flanges and unrealistic faces. Modern designs from firms such as Tangent, Eastern Seaboard Models and ScaleTrains are chemically darkened, finely profiled, and close in appearance to the prototype.
Choosing the correct wheel size is essential for both realism and performance. The general rules are:
| Prototype Wheel Diameter | Typical Use |
|---|---|
| 28″ | Modern auto racks |
| 33″ | Cars of 70 tons or less (and most cabooses) |
| 36″ | 100- and 110-ton cars and all passenger stock |
| 38″ | Intermediate wheelsets on articulated 125-ton well cars (end trucks use 33″) |
Wheel size alone is not enough. Axle length also varies between brands. Most manufacturers now list the measurement on the packaging or specify which trucks their wheelsets fit. If not, a quick check with calipers across the axle tips will tell you. Even a small mismatch can cause problems: an axle that is too long will bind in the sideframes, while one that is too short will move about and cause derailments.
| Axle Length (mm) | Prototype Diameter (inches) | Manufacturer | Code | Tread | Axle Length (decimal inches) | Notes |
|---|---|---|---|---|---|---|
| 13.64 | 33 | Intermountain Railway | NMRA RP-25 | 0.537 | MT | |
| 13.64 | 36 | Intermountain Railway | NMRA RP-25 | 0.537 | MT | |
| 13.64 | 36 | Tangent Scale Models | 502 (12) 503 (100) | Fine | 0.537 | |
| 13.72 | 28 | Eastern Seaboard Models Corp. | #920300 (12) | ? | 0.540 | |
| 13.72 | 28 | Scale Trains (Fox Valley Models) | Standard | 0.540 | ATH, BLMA, FVM, MT, SXT, TWX | |
| 13.72 | 28 | Scale Trains (Fox Valley Models) | FVM2801 (12) | Semi-Scale | 0.540 | ATH, BLMA, FVM, MT, SXT, TWX |
| 13.72 | 33 | BLMA | BLMA9810 (24) | Fine | 0.540 | |
| 13.72 | 33 | Eastern Seaboard Models Corp. | #920100 (12), #920160 (60) | 0.540 | Chart | |
| 13.72 | 33 | Scale Trains (Fox Valley Models) | Standard | 0.540 | ATH, BLMA, FVM, MT, SXT, TWX | |
| 13.72 | 33 | Scale Trains (Fox Valley Models) | FVM3301 (12) FVM3301100 (100) | Semi-Scale | 0.540 | ATH, BLMA, FVM, MT, SXT, TWX |
| 13.72 | 36 | BLMA | BLMA9815 (24) | Fine | 0.540 | |
| 13.72 | 36 | Eastern Seaboard Models Corp. | #920200 (12) | ? | 0.540 | |
| 13.72 | 36 | Scale Trains (Fox Valley Models) | Standard | 0.540 | ATH, BLMA, FVM, MT, SXT, TWX | |
| 13.72 | 36 | Scale Trains (Fox Valley Models) | Semi-Scale | 0.540 | ATH, BLMA, FVM, MT, SXT, TWX | |
| 14.05 | 33 | Eastern Seaboard Models Corp. | #920101 (12) | 0.553 | ||
| 14.05 | 33 | Scale Trains (Fox Valley Models) | Standard | 0.553 | ATL, CC, IMR, MDC | |
| 14.05 | 36 | Scale Trains (Fox Valley Models) | Standard | 0.553 | ATL, CC, IMR, MDC | |
| 14.05 | 33 | Scale Trains (Fox Valley Models) | Semi-Scale | .553 | ATL, CC, IMR, MDC | |
| 14.05 | 36 | Eastern Seaboard Models Corp. | #920201 (12) | 0.553 | ||
| 14.05 | 36 | Scale Trains (Fox Valley Models) | Semi-Scale | 0.553 | ATL, CC, IMR, MDC | |
| 14.05 | 38 | Eastern Seaboard Models Corp. | #920401 (12) | ? | 0.553 | |
| 14.07 | 33 | Intermountain Railway | NMRA RP-25 | 0.554 | ||
| 14.07 | 36 | Intermountain Railway | NMRA RP-25 | 0.554 | ||
| 14.30 | 33 | Scale Trains (Fox Valley Models) | Semi-Scale | 0.563 | Older Riv | |
| 14.30 | 36 | Scale Trains (Fox Valley Models) | Semi-Scale | 0.563 | Older Riv |
33″ Brass Insulated Wheelsets
for Micro-Trains® Trucks
Axle Length: 0.537″ 12 Axle Pack $14.95
60054 36″ Brass Insulated Wheelsets
for Micro-Trains® Trucks
Axle Length: 0.537″
BLMA
No longer available?
Eastern Seaboard Models Corp.
Precision-machined fine-scale chemically-blackened non-magnetic insulated metal wheelsets, with prototypical wheel faces. Operational on Code 40 rail without hitting the spikes. Made in China.
https://www.esmc.com/extra/instr/9200/9200chart.html
- https://www.nscalesupply.com/esm/esm-wheels.html – 60 ESM-920160 $52
- https://www.fiferhobby.com/n-scale-wheel-sets/ – 60 ESM-920160 $59.99
Scale Trains / Fox Valley Models (FVM)
PREFERRED?
Tangent Scale Models
- InterMountain Railway Co.
- Micro-Trains Line Co.
- Rapido Trains
- Athearn Trains (ATH)
- Atlas Model Railroad Co. (ATL)
- BLMA
- Con-Cor (CC)
- Fox Valley Models (FVM)
- InterMountain Railway Co. (IMR)
- MDC Roundhouse (MDC)
- Micro-Trains (MT)
- Scale Trains (SXT)
- Trainworx (TWX)
More Information
- Grivno, Cody. “Guide to N Scale Metal Wheelsets.” Model Railroader, Trains.com, 27 February 2024, https://www.trains.com/mrr/beginners/guide-to-n-scale-metal-wheelsets/.
- Kelly, Jim. “Wheel Quality Keeps Rolling.” Model Railroader, Trains.com, 3 June 2021, https://www.trains.com/mrr/how-to/nscale-insight/wheel-quality-keeps-rolling/.
Epilogue
Wheelsets may be small parts, but they are the foundation of a smooth-running railway. The conical tread and precise gauge keep vehicles centred on the track, reducing derailments and wear.
Full-size railways adopted larger, stronger wheels as loads and speeds increased, and the same logic applies in miniature. Metal wheelsets track better, stay cleaner, and add a subtle, realistic sound as they roll.
The development of N scale wheelsets from the rough, off-centre designs of the 1970s to today’s finely machined products is one of the quiet success stories of the hobby. It is a reminder that reliability often depends on the smallest components.