bcrawfo2

I'm building a new bike from the frame up. I'm getting a Trek Emonda (doing frame up so I can get a 64cm).
It says "28c Bontrager tires (with at least 4mm of clearance to frame)".
I'm looking at DT-Swiss ER 1600 SPLINE DB 32 which is 20mm inside and 24mm outside.

"The charts" say I can do up to a 19mm inside rim with a 28mm tire, but also say you can go a little higher. 20 seems a little higher, so assume it's ok.
I guess my real question is.....if I mount some random 28mm tire on that rim....is it going to be ok on that frame?
Or...do I need to downsize to a 25?

Thanks

cxwrench

I'd feel pretty confident that a 28 would fit but the only way to know for sure is try it or have someone post that has. I seem to remember that people used 28mm tires when I worked for Trek...maybe even 32mm.

August West

20mm should be fine. I like the DT Swiss tire/wheel chart and 20mm is the sweet spot according to it.

DT Swiss Tire Pressure and Dimension

Be aware all 28mm tire aren't actually 28mm when mounted. The 28mm Grand Prix 4000sII I used to run actually measured about 32mm on my 22mm ID rims. That is pretty extreme but it seems most run at least a little large.

squirtdad

Tires vary in size a lot. I had Michelin sevice course 25 that measure almost 28. My vittoria and continental 28 have measuer 28

also remember that the brake, not just the frame is key to tire size. So check the brake specs if you are using caliper (my 5800 105 say will handle 28 and do easily.....i have 30mm tubies in them now with no problem)

shelbyfv

Pick your tire, then research if it is reported to be true to size. As mentioned, the GP4000 was large for the nominal size. The replacement GP5000 is true to size. Ask about a specific tire.

fredjustison

@August West: I like that advice and good point!

bcrawfo2

Thanks everyone. Frustrating that they can't make a tire that matches the width more closely. I'll also head down to the bike shop and see how much space my frame will actually have. Maybe the tires they reference (28c Bontrager tires) run large or small.

ClydeClydeson

I'm sure many 28mm tires will fit, but not necessarily all.

Years ago someone lent me some 28mm knobbies for a CX race and those fit in my frame and fork, but I have a 28mm road tire (can't remember the brand) and it does not fit in my road frame.

Generally speaking, aggressive tread and flat protective layers add bulk to a tire and will make clearance tighter.

veganbikes

Can we be assured of anything these days? You may have clearance you may not, you might just have to install and test. That is the problem with cycling is it was driven by the pros who had bad data and we all assumed skinny tires were a good thing and we finally learned differently but we are still playing catch up. Sure we have big voluminous gravel frames that give more clearance and of course MTBs but road bikes are slower to catch up it is only more recently we are starting to give everything more clearance but sometimes it does stop at 28 and of course doesn't always go to the wider and thicker 28s.

Tomm Willians

Others may know more about this but I just installed a set of Veloflex Master 28”s on a bike and they look no bigger than some of my 25”s. I did not measure them but they certainly don’t look as big as a set of Continental 28”s my wife has on one of her bikes. I read in one post that someone found them to be closer to 26” than 28”.

The MuffinMan

Schwalbe One Evolution 28mm run true to size. Great tire - rubber not too hard. Even better/softer feel than Continentals which also run between 30 - 32mm marked 28mm.