33 or 38 tire for Gravel

Hi all

I have a Crux with TracerPro 33 on it and I use it for cx, for winter riding (on road) and this is the bike to take with me when I travel (not for travelling - for riding round the place where I travel) and those tires are great for that.

But I also want to participate in some Gravel races and I’m interested in how big the difference is between 33 TracerPro and for example Gravelking SK 38?

I would rather keep 33 so I don’t have to switch tires if the difference is minimal and 33 is fine for gravel.

I’d say 33 is certainly ‘fine’ for gravel. It MAY be best…but that really depends on how course the gravel you’ll be riding on will be.

depends on the ‘Gravel’ I wouldn’t touch a 33 for anything that actually has rocks on the surface. I run 43’s


“Back in my day” when gravel bikes weren’t a thing, we all ran 33mm cx tires for gravel. I can now say from experience that bigger is better, but depending on the terrain and surface you can certainly get by.


I personally like 37-40 range


Highly dependent on the “gravel” and your desire. 33 CX tires will be perfectly fine.

While I wouldn’t consider the San Diego Belgian Waffle RIde to be gravel, it is certainly very mixed surface and there is definitely gravel (and rocks) in there. I raced it in 2019 with 28mm Gatorskins (with tubes!) and I was happy with the decision*

*I am a VERY proficient mountain biker.

I roll the 32mm gravel king+ on a crushed limestone trail that I frequently ride when the weather’s nice and they work great. Plus they aren’t too bad when I switch over to pavement. However, whenever I ride these tires on proper gravel it’s sketchy.

Over winter I got some specialized pathfinders pros that I look forward to trying this spring. This kind of tire might be what you’re looking for. Most brands now seem to offer something slick or file down the middle with some intermediate and cornering knobs.

33s are a good compromise for your CX/gravel/winter riding case but 38s will be more comfortable. As others stated, a lot of it depends on the gravel you are riding. Another factor is your weight, if you are a heavier rider (like I am) go wider so you can run lower tire pressures. Unless you are racing UCI sanctioned races or elite USAC CX races like nationals, you could always just race CX on the 38’s too.

Have the exact same bike and had the same tires. I use it the same way as you, crux as a “winter racer” both on road and in the forrest. Had the same thoughts as you, and bought GK 38’s.
I thought they were heavy on road, and def. not very good in a bit of mud/slid. Did not find them more comfortable either. Prefered the tracerpros over these.
After ridden GK only a couple of times i switched to Challenge Grifo Pro 33 - they are absolutely class.
really think 33s are fine

1 Like

I think it depends on the quality of the gravel, and how long are your rides.

For tame gravel, and 2-3 hour rides, 33 will be fine. For rougher gravel, and longer rides, I think you’ll be better served with 38s.

I run 45s on my bike for rougher gravel/fire roads and long rides, 6+ hours.


33s are fine if you never actually ride on rough gravel or loose dirt. But I would go with the 38s to open your riding options. I have 40s on my gravel bike and I’m very happy with them. So much better off road than the 35s I have on a different bike. I must caveat with “I know nothing about CX”. Strictly a recreational riding perspective. I find the 40s very smooth on pavement and can’t imagine that they are any slower than the 35s in that regard (I’m not road racing anyone on my gravel bike). And I can ride non-technical mountain bike trails easily with the 40s…a bit more sketchy with the 35s. I guess I’m in the camp of “fatter is better” these days based on my own non-competitive road and gravel bike experience. So the 33s could fit the bill if you are confident in your riding environment, but I recommend fatter if you want a wider aperture of riding options for this particular bike.

1 Like

Unless it’s pretty smooth and no rocks, I’d go with the 38c.

I have a pair of 35c gravel tires I put on my road bike for gravel, but I can see the gravel bikes with the larger volume tires seem to handle the rougher sections better.

33’s can be a good choice for some gravel. I’m thinking ‘hero gravel’. Or mixed surface.

If it’s just typical crushed limestone, river gravel, loose stuff…you’ll regret not going with the gravelkings. But you could still ride it with the 33’s if performance isn’t a primary concern.

For the better part of a decade I rode many miles on bikes with 1.25" wheel…or about 32mm…all on gravel. No prob. But also, not racing.

It looks like I’m late to the party (as usual).
As several others have noted the type or condition of the gravel makes a difference it what tire will be most comfotrable and/or provide the best traction.

I’ve used 33c CX tires in the past and they will work fine. I wouldn’t choose to use anything smaller than 38 and right now I have a pair of Maxxis Re-fuse 40’s on my gravel bike. They are super comfy and very fast on my local gravel. Last summer I used them to head to the Ozarks for a weekend and after about 3 miles knew they were not the right choice.
If your gravel is fairly hard packed or VERY chunky a semi-slick or file-tread work great and roll fast. When you get to places where there is small particle size gravel and a loose layer on top you have to have some knob. Pressure can and will make some difference, but in some cases you just need some more gription.
This year when I go to the Ozarks I’ll be rolling my Maxxis ramblers.


WTB Riddler 37’s at 40psi have been game changer for my gravel rides here in New England (bad roads, singletrack actual gravel, sketchy stuff)

I just did a “Groad” race in Austin over the weekend on 32mm Terravails (semi slick, measure closer to 35 on 3.4 AR’s). They were excellent on pavement and the hardpack gravel, but there was some snow/ice/lots of mud and I was wishing for wider and knobs for sure. As said many times, if you can fit wider and aren’t as concerned about all-out speed, do it.

Not even going to bother reading all of the (likely valid) replies before I jump in: If you’re a buck-O-five, 32 is fine, if you’re a buck-and-a-half, 34 or 35 should work, if you’re two bills like me, 38 is better and 44 is niiiiice.

Oh, and those numbers are based on my experience with Iowa (township/county/sub-region) specific gravel, YMMV on Iowa B-road, on any change between rural gravel and “Amish/horse-hoof friendly” gravel vs counties without any Amish population.



Pathfinders are awesome. I switched to them from Gravelking SKs at the end of last year. Basically feel like a road tire on pavement, yet performed well on gravel.