How (& Why) to Replace Old HO Scale Plastic Wheels With Metal Wheelsets

This article will explain:

  • Benefits of replacement wheels for your rolling stock
  • Drawbacks of plastic wheels
  • When you’re on a budget…
  • Intermountain wheelsets, the A+ choice
  • The New Standard – RP25 Wheel
  • Walthers metal wheel sets, an economical option
  • Bowser metal wheels, an old favorite
  • Wheel diameter basic guidelines
  • How to replace model train wheels

Looking for a quick & easy way to upgrade the older rolling stock on your model train layout? Consider replacement wheelsets to swap out the wheels on some of your favorite freight cars. While some cars today are still produced with plastic wheels, many have switched to metal wheel sets.

The Benefits of Replacement Wheels for Your Rolling Stock:

  • The cars tend to roll easier because they have less resistance
  • Since they roll more smoothly, you may be able to pull more cars
  • Durable, can handle track imperfections on your model railroad layout better than plastic
  • Offers a higher quality, more realistic visual appeal than original plastic wheels
  • Easier to keep clean vs their plastic counterparts

What are the Drawbacks of Plastic Wheels?

  • They produce greater friction on the track, are prone to warp
  • May lack the realism metal wheel sets offer & aren’t as durable
  • Not as noticeable sound as the wheels cross rail joints
  • Tend to collect more dirt & dust – which isn’t just a cosmetic problem…
  • That extra dust can lead to electrical troubles or even derailments

If an authentic “clickety clack” sound is important to you, metal wheels are more likely to produce the familiar sound we all love as they cross over the rail joints on your model railroad layout.

Intermountain Wheelsets (and Walthers, and Bowser…Oh My!)

If you’re budget conscious, it’s worth nothing that while it’s relatively inexpensive to replace wheels, the cost can quickly add up if you have a large number of rolling stock to upgrade. One simple approach is to only do a few replacements at a time. Also consider buying your wheel sets in bulk for added value.

The top 3 manufacturers we carry that offer replacement wheelsets for HO scale rolling stock are highlighted below, along with some specs. Which to choose is up to you.

Intermountain Nickel Silver Plated Brass Insulated Wheelsets

Intermountain Wheelsets are typically considered the top-of-the-line as far as replacement HO scale wheels go. A few general highlights:

  • Wheelsets are available in O, HO, and N-Scale
  • All HO scale wheels follow NMRA RP-25 standards
  • The whole wheel set is non-magnetic; one wheel is insulated from the metal axle
  • 006″ (+- .004″) axle length
  • Finished in a dull, blackened appearance that is more life-like
  • Can also be weathered if that’s the look you’re going for

Here’s a helpful chart adapted from Intermountain’s website – use a caliper to measure your wheel diameter. (Note: HO scale is 87.1 times smaller than your prototype).

Wheel DiameterHO Scale MeasurementWhere Used?
28”28/87.1=.321″Modern Tri-Level Autoracks, some Bi-Level Autoracks, some older intermodal cars such as Impack spine cars, front runners & four runners
33”33/87.1=.378″50- & 70-ton capacity cars (CAPY* approx 150,000 lbs or under); cabooses (depends on prototype)
36”36/87.1=.413″100-ton capacity cars (CAPY approximately 200,000 lbs); also on all passenger cars regardless of era; cabooses (depends on prototype)
38”38/87.1=.436″150-ton capacity cars; primarily the center connection trucks on modern intermodal cars that use 33″ wheels at the coupler ends
*Find the CAPY info easily to use as a guide – it’s usually printed on your freight car. Some cars will have the wheel size printed on either the side or ends of the car.

The New Standard RP25 Wheel, Developed by the NMRA

Developed by the NMRA (National Model Railroad Association), the RP25 wheel specification set a new standard. RP25 (an acronym for “Recommended Practice”), was created for a more accurate appearance, and optimized performance. Now the standard size wheel used on all North American models, the RP25 is even a requirement at some model railroad clubs.

A little history on what drove the RP25 standard: Not long ago, models came with flanges of varying depths. Way back, Code 100 was the industry standard HO scale rail height. But as HO scale gained more precision, Code 83 took over as a more authentic mainline rail height.

When this happened, something interesting was observed concerning flanges (the “lip” that which travels along the inner rail, allowing the train to be steered by the rail): cars that had deeper flanges (and that once had zero trouble rumbling over Code 100 rails) seemed to go berserk: running into rail joints and switches, and even derailing. While it would seem that a deeper flange creates a smoother ride, it can actually instigate more trouble.

Pretty interesting, isn’t it? Moving on…

Walthers Metal Wheelsets: A Solid, Economical Choice

If you’re on a budget, WalthersProto HO Scale 33″ Turned Metal Wheelsets with Metal Axles may be the solution you’re looking for. They’re a quick, cost-effective solution to upgrade your equipment. Walthers’ popular 100-packs of RP-25 wheelsets make ideal replacements for the ones most often used on freight cars.

  • Turned metal RP-25 wheels deliver better performance on the track
  • The standard wheel size fits steam, diesel and modern-era rolling stock
  • Ultra-smooth rolling metal needlepoint axles
  • One side is insulated
  • A 100-pk can upgrade up to 25 of your favorite freight cars

Bowser HO Scale Metal Wheel Sets

For over 50 years, Bowser has been well-known in the model railroading industry as a manufacturer of HO scale freight cars, diesel locomotives, brass and plastic detail parts, and more.

Bowser offers metal wheels with needlepoint axles in packages of 20; choose between 33” or 36” wheel diameter. Each package of 20 wheels can upgrade up to 5 cars. Wheels are non-magnetic with RP25 flanges.

Wheel Diameter Basic Guidelines

Puzzled about which size to choose? Easy: just replace the wheels that are currently on your freight car with ones of the same size.

Take a look at an HO scale locomotive. Typically, it will have a bigger wheel diameter than the cars it is pulling.  Though this may be more obvious on steam locos and passenger cars, you’ll also see it even on modern diesel locomotives. ModelTrainStuff reports explains the bigger surprise is that there is also variation between the wheels on rolling stock.

You can check out the helpful table adapted from Intermountain below, but here are a few general guidelines:

  • Passenger car wheel diameter can vary; most use 36” wheels.
  • Freight cars can be a bit more complex; 33” wheels are common, especially if the car is circa the 1970s or earlier.
  • Today, heavy-load cars (covered hoppers; 60-86′ boxcars) often use a 36” wheel diameter.
  • Some special load cars (coil cars, Flexi-Flo hoppers) run wheels as large as 38′. These include coil cars and Flexi-Flo hoppers.
  • Smaller cars (Intermodal Well Cars, Autoracks, etc.) commonly use a 28′ diameter, which accommodates a lower profile for extra height loads.

How to Change the Wheels on Your Rolling Stock

Fortunately, swapping your old plastic wheels for a new set of metal ones is a simple process.

Tip: You may find it more approachable to swap out the wheels with the truck removed from the car.

  • On plastic trucks, carefully spread the side frames outward until you can pop out the wheels and axle.
  • On metal trucks, additional disassembly may be required.
  • On sprung trucks that have springs positioned between the side frames and bolster, pay attention not to let the springs come loose.
  • Most replacement wheels can be press-fit onto the axle for easy installation and removal. Only moderate pressure is needed.

Who would have thought there was that much to say about a simple wheel, right?

Looking for an HO scale brass locomotive or need a bulk pack of Intermountain wheels to upgrade your rolling stock? See what replacement wheelsets Nightwatch Trains has in stock. New listings added daily!