1940 K5 wheel swap

Anybody know an easy way to update wheels for my K5? They're not widow maker wheels but they are split/ lock ring style. I'd like to go smaller diameter from the 20x7, maybe down to an 18". The wheel bolt pattern is 6x10", the drums are 15's. Huge. I wonder if they make a wheel adapter or if anybody has other ideas???

There is no way you can go smaller without changing the hubs on the front and rear, or do a frame swap. What you are calling the wheel bolt pattern is the drum mounting. The "spider" you see in the center of the rim is the brg hub and rim mount. The clamps are the actual wheel "bolt pattern". This is a typical mounting style for the older medium duty trucks.

I don't know what your plans are for the truck but if the tires are decent they will last for a long time. they won't ride real smooth like the radial tires of today though.

Glenn

Sooo...I still have the adaptors for THAT very truck to convert to five hole Budd 20". Front only.
What is your vision for that truck?
You can adapt another I beam front axle. It can come from Chevy, Ford, Dodge, IHC 1/2 to 1 1/2 ton. They are all so similar. You will need to adapt draglink and drill new holes for spring u bolts.
Any bolt pattern you like. 1.5 ton fenders look will look kinda funny with 1/2 ton wheels unless you lower it.
I put 1968 IHC 1 ton axles under a D-30. D-30 is VERY similar to your truck. Those axles made all the difference in the world in driveabilty.

Hm, What's to stop a guy from Re-drilling the drums and pressing in studs like modern drums, at whatever bolt pattern makes sense? The tires look good but they've got a lot of dry rot cracks in them from sitting for almost 20 years. They were new then. I'm considering getting rid of the leaf springs altogether and installing mustang 2 style front end. I really want it low.Not sure what to do with the rear, I may do a monster c-notch in the rear and flip the axle, maintain the load capacity and have a really really slammed ramp truck. Those wheel adapters sound interesting. I wonder if they make 'em for the rears?

I don't think a Mustang II front end will be strong enough for that large of truck. Even unloaded the weight on the front end is more than a pickup.

The extra weIght is in these wheels,drums, rear axle, and a bit in the frame. It LOOKS massive but that's mostly sheetmetal and sheetmetal isn't that heavy. The engine is basically the same as a pickup. Truck radiator IS heavier than pickup.
I've "converted" five or so old 1.5 ton trucks to 1/2 ton. You'd be surprised at really how close in weight this era pickup and truck would be minus hefty big truck bed, wheels, drums and rear axle.
For example, the 1934 Chevy 1.5 t truck I converted to pickup is so close in size and weight to a 1934 Chevy pickup as to be neglible. Same with the 1934 Ford 1.5 ton.
INTERNATIONAL TRUCKS are indeed built heavier, stronger than the others. Still, very close in weight between bigger truck and pickup if you subtract the stuff you weren't going to use, anyway.
(Edit--YES I cut off the back end of 1.5T frames after moving wheelbase up)

I was gonna say.. The front of this truck is lighter than my dodge d150, it's only a straight 6. I can push the whole truck around by myself, they're big, but compared to modern vehicles, they're 1/3rd less weight. Ifs front suspension all day.

The answer here is of course (what took a bit investigation), Accuride still makes a demountable rim for tubeless tires that bolt straight to this 5 lug hub. It's kind of amazing. Now I just need to find a 50 series tire for a 22.5 wheel. So this is an option if you want to maintain the stock look, I'm considering the conversion adapters munsonmotors has too, just need to make sure they're compatible.

Please post pictures. Sounds very interesting. I didn't know about any other options to the cast spoke wheels. (Besides my adptors).
Remember that the cast spoke type wheels you have have the hub integrated INTO the wheel. The drum bolts to this assembly. Different to what we're used to on light duty stuff. REALLY limits "bolting" anything on. It has to come with appropriate hub or you need to source another hub.
NOT IMPOSSIBLE. Just not done everyday.
Believe me, we are watching your progress. Good luck!

The problem you will run into is: modern tubeless demountable rims are too wide to clear the tie rod in the front and for the duels in the back. Your 20" rims are somewhere between 5 and 6.5" in width (inside, from bead to bead) where as the 22.5 tubeless are not to be had in under 7.5" width unless I'm mistaken.
The rear spokes aren't wide enough nor spaced out from the frame enough to take a wider rim.
Your choices are: clean and re use your rims with new tires, replace the hubs with equally hard to find narrow disk wheel hubs (this is what MM is calling "adaptors") or put new axles under it.
BTW there were "adaptors" that bolted onto a "Budd" (Disk wheel) hub that would allow you to run spoke demountable rims, Scarce back "in the day" and almost impossible to find today. There were never "adaptors" to go the other way for obvious reasons. Spoke hubs and rims are much stronger than disk wheels, which is why they were popular when roads wern't so good.