Trike 20" tires does 20 x 1.35 vs. 20 x 1.50 fit rim?
 

New to trike and small 20" tires. I had originally 20 x 1.35 tires, the new ones are 20 x 1.50. My question is will they fit my rim the same (I'm thinking they will)?

My new tires are: Schwalbe Marathon Racer 20x1.50 (40-406)

Check this chart for acceptable tire widths for each rim width: https://endless-sphere.com/forums/vi...hp?f=3&t=67343 If you are confused about how to measure rim width, go to the Sheldon Brown website and see the section on rims: https://www.sheldonbrown.com/rim-sizing.html

When I bought my Catrike 700 it came with Schwalbe Ultremo 23 X 406 and I had no trouble at all switching to 1.4 X 406. Have over 10K miles without a hitch. That's going from 0.9" to 1.4".

I've had 1.35 and 1.5 inch tires on both Velocity and Jet Set 406 rims.

That's a nominal difference and they should fit just fine. Just FYI, rim manufacturers often list "Optimal" sized tires that fit on a given rim.

My new trike came with Kenda Kwest 20x1.50's, they seem kinda thin and delicate as my shortest and flattest way into Colorado Springs from Security is the Pikes Peak Greenway Trail, lightly rutted gravel/limestone mix, was thinking of changing to Schwable Delta Cruiser Plus's in a 20x1.75 for more "tread" on top and maybe a bit more "tire" on the trail/road! Anyone see a problem with that? Thanks! (Trike: Sunseeker Eco-Tad SX)

Kwest are probably heavier than Primo Comet. But yes if you aren't on pavement then a heavier tire is warranted. Hostelshoppe shows several 406 size tires with tread.
https://hostelshoppe.com/store/filte...-inch-(406mm)/

Here's a comparison between the Primo Comet which comes in both 1.35" and 1.5" widths, the Kenda Kwest 1.5" and the Schwalbe Delta Cruiser with most of the data from Niagara Cycle and Bike24 websites. The Kenda Kwest 193 is a common tire that comes as OEM equipment on trikes. It was standard on my first trike and I bought them more than once as replacement tires. It is not a fragile tire. I would get around 3000 miles between replacements. I have used the Primo Comet 406 X 1.35" as a front tire on two different recumbent bikes.
Bike24 lists the weight of the Schwalbe tire as 675 grams. That's a lot considering you will be using three of them. Here's the list:
Primo Comet 406 X 1.35" Recumbent tire - a fast rolling, high pressure tire.
Item Specifications
Weight 280g
PSI 100PSI
ISO Diameter 406 / 20" BMX Labeled Size 1.35"
Primo Comet 406 X 1.5"
Item Specifications
Weight 342 grams
Labeled Size 1.5"

The Kwest High Pressure Road 100 PSI 406 X 1.5"
445 grams. Ideal for Recumbents!

Fact Sheet of Schwalbe Delta Cruiser Plus Active Wired Tire - 20x1.75 Inches - Black-Reflex
Dimension: 47-406 (20 x 1.75)
Weight: approx. 670 gram (manufacturer information)

I've been wondering this myself for a road bike that I've been working one. I knew the tires I had, but had to pick the right wheel. So, I used this chart:

THE RIGHT TYRE WIDTH ON THE RIGHT RIM WIDTH - Engineerstalk : Engineerstalk

I measured the outside, subtracted 5mm, and figured out my internal width (I didn't want to remove the tires just to measure, so, kind of a "guesstimate").

I'll second any good opinions on using Primo Comets. Good tires, not the best for grip in the wet. But, you're on a trike, so have fun drifting! LOL!

I can only use comet 20x1.35s in the front due to clearances, and I run the 26 inch Primo racers in the back. Very comfortable set for long distances. Only had one flat on my current set.

There's a 451 rim (maybe 452, I forget)- anyway, it's a skinnier tire that doesn't interchange with the 406's. With the 406's, they should be pretty interchangeable.