how much clearance is enough?

[kmac]

apologies if this has been asked before... i couldn't find anything exactly like what i was looking for.

i have a traditional road bike, and have had continental 4-season 25mm tires on hed belgium c2 rims (width 23mm). i've been wanting to move up to 28mm tires (still conti 4-season), and the old ones are finally worn down enough that i can justify the swap.

i put them on today, and the clearances are... tight. there's no rubbing or anything, but there's not a lot of wiggle room. at the front there's maybe 2-3mm at the top of the fork, and on the back, another 2-3mm at the brake.

is this a situation where if it fits, i have nothing to worry about? i probably only had like 5-6mm clearance before, but i didn't know if cutting what was already a small amount in half is asking for trouble.

i attached a few "after" pictures, but it's really hard to tell anything. maybe they'll be useful to someone here (turns out it's REALLY hard to take pictures of tire clearance).

thanks in advance for your guidance!

[ultraman6970]

It clears, all good

[joosttx]

You are fine. 2mm maybe 1.5mm is about the minimum IMO.

[zennmotion]

Should be good enough if you stick to dry pavement, you may pick up debris on wet shoulders or short bits on damp unpaved sections. I put strips of helicopter tape on the insides of my chainstays and under the fork bridge on my carbon bike, even though that further reduces clearance, I'm a little OCD about grinding tire against carbon. BTW,28c Conti 4 seasons are not fully 28mm on my 21mm rims,- maybe on yours. But a different, "true" 28mm tire may not fit. I'm not a fan of 4 seasons anyway- they're durable but don't ride great, not great on wet roads, and they're overpriced IMO. I have similar clearance constraints on my Cyfac, my go-to tires are Michelin Pro 4 (front)/Pro 4 Endurance (rear). The 25c width measures out to 26-27mm, just right for me. They wear faster than 4 seasons, but otherwise better in every way and less expensive- maybe look at these or another tire (Schwalbe, Vittoria?) when your new Contis are dead.

[simplemind]

All depends on where you're riding, gravel or road. No mud, then 2.5mm prolly enough, but if mud is involved, then 5mm is minimum. That's assuming the wheel is true. ;)

[fa63]

I like to leave at least 3 mm on all sides. I believe the ISO standard calls for 4 mm min on road bikes.