Recumbent - Schwalbe Big Apples on 24 in (507) - Outside Diameter

Can anyone tell me the effective outside diameter of a 24 in. (ETRTO 507) wheel mounted with a Schwalbe Big Apple or similar approx. 50mm (2 in.) slick or semi-slick tire?

By "outside diameter," I mean the measurement across the full width of the wheel, from tread to tread, through the wheel axle, with the tire mounted and inflated. There may be a more precise term for this measurement, but I don't know what it is.

I don't have any experience with this wheel size, and while tire bead or rim diameters (ERD) are easy to find on the web, it's harder to get specs on the overall diameter of mounted tires. I posted the same thread on the Mountain Bike forum but have had no answers, so I thought I'd try here as well. Thanks.

Tires are generally about as tall as they are wide, perhaps a bit taller. I have a 20/26" bike and 2"/2.3" Big Apples for it but they're not mounted right now, so I can't measure them. I would guess 2.1 inches tall, for a 2" wide tire.

Also note, if you have fenders, you may have problems fitting tires over about 1.75" wide. The bike I have is a Cycle Genius Falcon with Planet Bike fenders (the fenders themselves are only about 1.75" wide).
---The 2" wide tire on the front fits just fine without bending the wires at all, but the 2.3" wide tire would probably rub on the fender wires. There appears to be enough length to spread them a bit however.
---The 2.3" wide rear tire would rub on the upper fender-mount bolt unless the lockwasher and washer were removed. I also had to make new/longer fender wire braces for the rear, as the standard ones were not long enough (they have to rise straight and then angle in sharply to clear the tire). The brace wire is 1/8" dia rod, and you need to heat it with a torch to bend the small loops for the mounting eyelets.

....Also with the 2.3" tire mounted, I would get some chain rubbing if I used the couple lowest granny gears (small chainring and largest cog). The Big Apples are great at low pressures if you're going to be riding over rough ground, but (-assuming you can even get them on at all-) most multispeed bicycles just aren't really built to handle them and you do run into little problems.
~

Thanks for the info, Doug, it's helpful.

The project that I have in mind does not involve fenders, and, as best as I can tell, there's plenty of frame clearance. Based on your observations, I'll check the chain line.

Assuming that the 24 in. x 2 in. Big Apples have the following published ETRTO/ISO specs - 507 x 50 - and assuming that the 50mm wide tires are about 53 mm tall, do you think it's reasonable to estimate the overall diameter of the wheel like this:

ERD + Tire + Tire = Outside Diameter, thus

507 + 53 +53 = 613

Your thoughts are appreciated.

Thanks, PuttPutt, that's very helpful. It's a full inch larger that my current set up, which uses ETRTO 520 rims and 520-29 Red Rider tires, which, to my estimation, are far too narrow. By the way, what sort of 2 in. slick are you using and do you like it?

I'm running a thread here concerning the same problem: That is, fitting the Big Apples on my Cycle Genius CGX Starling recumbent. I'm mostly concerned with derailleur clearance on the granny gears. The rest, I think, will be OK. I don't use fenders. The Big Apples appear to be not too high, but wide. I ordered the 2.0's for front and rear ( 16" and 20"). One idea I had was to try and stuff bunched-up newspaper or some similar thing into a tire cross-section to take a measurement before I mount the tires, as you can not return a tire that has been mounted.