Rutherford

My bike's an inexpensive fitness/hybrid Diamondback, and I like it a lot. But now I want to equip it with wider fatter tires for a cushier ride, and so it is better suited to the occasional route over dirt roads.

Here is what is on the rims: 700Cx28C/38C ETRTO 622 x 19

Here is what is on the Kenda Kwik Trax tires: 32-622 32c 28 x 1-5/8 x 1-1/4

The tires measure 1-1/4" in width. I measure the spread between brake calipers, opened for change, (rim brakes, not disc) and it looks like a tire of 1-5/8 (40 mm) inflated width can get between. A tiny bit fatter, maybe a 45 mm, if mounted not-inflated, and blown up after. The bike has no fenders, and clearance to forks and frame is plenty adequate for fatties at 1-3/4" width.

My existing tires have tubes, and I intend to use tubes in whatever fatter tires I put on the bike.

What size would you suggest is the fattest I can go without negative effects.

ofajen

The tire that leaves at least 3mm clearance of the tire from all parts of the bike, including fenders, fork arms, crown/front brake, chainstays and rear brake/bridge if applicable. Consider both increase in tire width and overall increase in tire outer diameter.

Otto

SpedFast

You are only limited by the constraints of your frame and brake calipers. Like ofajen stated, consider both the width and height of new tires. I definitely agree with wider tires if you're not sticking to asphalt. The ride difference is amazing.

Rutherford

Here is what I put in my checkout basket, not yet cliicked the BUY button yet: Kenda Flintridge Pro 700 x 40c

Still trying to decide.

VegasTriker

You can get all the information you need to make a safe, intelligent choice at the late Sheldon Brown's website: https://www.sheldonbrown.com/tire-sizing.html. If you scroll down until you see the chart in red and green you will find the maximum tire width that your current rims can accommodate. Before you buy, you also need to figure out if the tire will fit the space between the fork blades and rear part of the frame. Sometimes that is the limiting factor even though your rim may still be safe with a wider tire. The link has a lot of good information on how to measure rim width correctly.

PDKL45

The answer's in the numbers in your post. Do you know what they mean? 700Cx28C/38C ETRTO 622 x 19 means that the rim's diameter is 622 mm (700c or 29er size) and the "19" in 622 x 19 is the internal width of the rim, 19 mm. So a rim with a diameter of 622 mm and an internal width of 19 mm. 700Cx28C/38C is telling you that the rim likes tires between 28 mm and 38 mm wide.

The Kenda Kwik Trax tires look like they're 700c x 32, so 32 mm wide.

With the measurements you've done, it looks like 700c x 38 - 700c x 42 tires will fit. Personally I'd recommend Schwalbe Little Big Bens, 700c x 38. Look at the Rivendell website, or go have a look at Chain Reaction Cycles, Bike24 or bikediscount.de, the European online retailers. Get the black version, rather than the brown or cream; they're lighter and much more lively to ride.

Camilo

Might be a good reason to use a local bike shop even if the tires aren't the cheapest deal you can find online. You could take the bike in and have them help you pick the fattest tie tire that can fit on your frame and fenders.

One thing about the brake calipers and whether the tire will fit inflated or deflated. If you don't need to remove the front wheel regularly for transport, it won't be much of a hassle to install the wheel uninflated and inflate it. If you regularly remove the wheel for transport like I do, you'll get tired of having to pump up the tire frequently which would be a good reason to limit yourself to a tire that doesn't have to be deflated.

I rarely buy tires locally since I know exactly what brand, model and size I'm looking for. But this case might one for on the spot assistance and fitting even if it costs a few bucks more.