Wheel size is based on the weight of the car and load.  Older cars of less than about 50 ton (maybe up to 70, I'm not 100% sure) would have 33" wheels, modern cars of higher capacity, and almost all passenger cars, have 36" wheels.  28" wheels are used primarily on tri-level autoracks, to get the floor lower and increase the loading capacity.  The cars, even fully loaded, don't weigh enough to be a problem on the smaller wheels.

So, I would put 36" wheels on all your passenger cars, and any modern freight cars.  If you model the modern era, you can almost get away with nothing else.  Older eras need a mix for freight and passenger.  In my era ('40s) almost all the freight cars are on 33" wheels, but all my passenger equipment is on 36"

I would not recommend Exact Rail. Intermountain makes a couple offering of wheels and trucks that work great.

Basically use 33" for 70-ton or under cars, and 36" for most cars over 70 tons, plus passenger cars.  Some special situations like tri-level autoracks or spine cars can get 28".

There are several good brands of machined metal wheels, all of which should perform well.  ExactRail and Intermountain are both excellent, and I've had good luck with the wheels in newer Athearn RTR and Genesis cars.  Walthers and Atlas machined wheels perform well enough but have odd face contours that look a bit strange (although they aren't overly objectionable to me when painted). 

Kadee and older Proto 2000 wheel designs are cast metal and can have problems with uneven wear and dirt accumulation, plus I've seen quite a few Proto 2000 wheels that weren't mounted properly on the axles and wobbled.  I also have tried JayBee wheels and haven't been impressed with their rolling qualities compared to other brands, so haven't purchased any after my initial batch. Note that all these are metal, but not necessarily steel.

It's rare to find a steel wheel on a model railroad in the Us.  They are attracted to uncoupling magnets, which has been known to cause interesting issues.  I find it odd that a club would require steel.

Are you sure you don't mean just metal wheels?  Most are nickel silver, or NS plated brass.

One more vote for Intermountain or Exact Rail. The two manufacturers make what appears to me nearly identical wheels.

The preference difference for me is that I can find narrow tread Exact Rail wheels in bulk. Under a boxcar, flatcar or a gondola, the wider tread wheels are barely noticeable. When running tank cars or intermodal cars, I prefer fine tread wheels. The nicer scale appearance is truly apparent. Some people say that the thin wheels do not preform as well, but the Proto87 guys will probably agree that has more to do with the track than the wheels.

I should have said METAL. Thanks for all the input. As most of my cars are the 1930's up to the very early 1950's I will be getting 33" and 36" for my passenger cars. Haven't checked out Intermountain yet and would like to patronize one of our advertisers who has good pricing and/or discounts.

I may leave Derlin wheels on cars used on my railroad which serve as "static' scenes as they won't be traveling. Never knew that these type of wheels left "goop" on the track requiring frequent Bright Boy cleaning. . . .

For what it's worth, I now install intermountains by default on my rolling stock - even if they come with other metal wheels.

As mentioned, it's probably a track issue, but I find the Intermountains to be a lot more reliable on the layout (ie derails disappear).

I haven't had a chance to try the exact rail wheels.

Per patronizing our vendors, you can order intermountain wheels from Dallas Model Works - I'd recommend a bulk set, if you decide to go that route.

David, forgive this long post, but I hope there's good information here for everyone on this topic.

Perhaps my observations from years of trials and tribulations with regards to replacement wheels and trucks might be of interest to all. I'm the head of equipment inspection at our club, and due to the nature of our layout (multi-deck mushroom design over two floors interconnected with helices) our club standards had to be quite demanding to maintain smooth, trouble-free operations. So we're kind of a harsh proving ground for what works in terms of wheels and couplers.

As soon as we built our first helix, we discovered free-rolling, non-magnetic metal wheelsets were the only solution to get 40-car trains up a corkscrew with a continuous 1.6% grade. And aside from greatly reducing friction, there is the pleasant finding that metal wheels don't collect dirt like Delran plastic ones.

However, not all manufacturers metal wheelsets are created equal.

From experience, the best overall replacement sets are from Intermountain and Reboxx. And from the limited experience we've had with ExactRail, their wheels are great too. All these are machined (not cast) with needle-point axles; and that makes a big difference.

Intermountain, as you are aware, offer regular RP-25 and semi-scale wheel treads, in 28'', 33'' and 36'' diameter sizes. If your club uses pre-fab Atlas turnouts, code 100 or 83, I would advise you stick to regular RP-25 profile wheels. The semi-scale wheels can end up causing derailments in these turnouts. If your club hand-lays switches to NMRA standards, then the semi-scale treads will be fine. For your era, as others mentioned, you probably only need to buy 33'' wheels for freight equipment, and 36'' for passenger cars.

Reboxx wheelsets are specialized equipment, and from all I can see are made by the same factory as Intermountain's wheels. They look exactly like them, and come in the exact same style packaging. However Reboxx differ in that they offer different axle lengths, versus one-size-fits-all Intermountain. This is important if you are replacing the wheels on brass rolling stock. Also older Athearn (pre-Horizon Hobbies) trucks have wider axle spacing which cause Intermountain wheelsets be pushed up somewhat into the sideframes. They still work, but not optimally. Reboxx wheels with 26.29mm axle length are the direct replacement for older Athearn truck sideframes.

These new ExactRail wheels are probably up to par with Intermountain/Reboxx. I can only assume that with the dozen of so ExactRail cars we have currently in operation on our club layout. We don't have the same years of experience with them, but there have been zero issues so far. Given their company's reputation, I'd say these wheels are at least equal to Intermountain quality with the added bonus of being closer to scale appearance. However keep in mind that ExactRail's wheels are semi-scale, so they may cause issues in Atlas pre-fab turnouts.

Other replacement wheelsets out off the top of my head are from Kadee, Proto-2000 and Jay-Bee.

In terms of the cast-metal wheels Kadee's are the best. I've never seen a bad Kadee wheel from the manufacturer (I have from almost all others). Problem with them is they do not have needle-point axles, so unless they are in Kadee truck sideframes they will probably give you the same friction as plastic wheels. That may not be an issue with your club, but it would be if you are trying to run long trains up substantial grades.

Proto-2000 wheels were initially awful. Their very first products were plagued with manufacturers defects. Even though they've been improved (they had to) I've always held them in suspicion ever since. To this day out of 4 wheelsets you are bound to get 1 or 2 with a slight wobble. That's not an issue with 10-to-20 car trains with nominal grades, but 30-40 car trains on helices demand wheels that roll dead straight.

Jay-Bee wheels claim to fame is they have non-magnetic axles. However regardless of the manufacturing quality of their products, their axles are not as free-rolling as our club requires. So we've avoided their wheels, and I can't comment fairly about them.

Finally, a bit more of an expensive option, but if you need to replace entire trucks there are high-quality companies who do not sell their metal wheels separately, but they do offer entire trucks. This includes Kato, Kadee, Atlas, and Athearn (post-Horizon sets). You can buy with confidence from any of these companies.

A note of caution, Kato wheels are always slightly under-scale (as in 100% of them right from the factory). Not a big deal with pre-fab turnouts, but with hand-laid ones to NMRA specs they will bump and click through the frogs. Good news is you can tug the wheels into gauge easily enough.

Proto-2000 trucks are also available separately, but again because of the occurrence of some wheels with slight wobbles in their products, we tend to avoid them. Better to spend a little extra and buy other sets with very few (if any) imperfections from the factory.

To finish this long-winded post, I need to remind all that our club is very demanding with our equipment standards. So please consider my observations here as the extreme rather than the rule. That said, if certain wheels work great on the WRMRC layout, they will probably be equally great on any layout.

Cheers,
Ted

Double stack container car sets will often run 36 inch wheels on the end units and 28 inch wheels on the intermediate cars.  The best bet is to replace your plastic wheel sets with the same size metal wheel sets as came from the factory on your model.

Double stack container car sets will often run 36 inch wheels on the end units and 28 inch wheels on the intermediate cars.  The best bet is to replace your plastic wheel sets with the same size metal wheel sets as came from the factory on your model.

That's NOT correct. Every stack car I've ever photographed has HEAVIER intermediate trucks under the articulation points between units, since the truck is supporting not one but two cars. Most modern stack cars have 125 ton trucks at these points, and 100 ton trucks on the ends.