KonaRider125

I am considering replacing the 25mm tires on my road bike with 28mm tires. I am unsure if 28mm tires will fit my bike(Nashbar carbon), I attempted to ask the manufacturer and they would not give me a definite answer so I'm turning to you guys for help before possibly wasting $100+ on new tires/tubes.

How much tire clearance should I be looking at around my current 25mm tires to know if a 28mm has a good chance of fitting? Thanks for the help.

soloist_huaxin

go to LBS and ask them(nicely) if they have 28mm tires to try on? tires can and will vary in size. i.e. conti 28mm is different than michelin 28mm, etc.

SquidPuppet

The new tire would be 1.5 mm closer to each of the stays and insides of forks. It would be 3mm closer to the top of the fork, the rear brake bridge, and the bottom bracket. Look, measure, decide.

This is accurate if your current tires measure a true 25mm and the new tires measure a true 28mm.

FastJake

It is impossible for the manufacturer to give you an answer because tires vary in size, despite published specs, and it depends on the rim you mount them on. You can use the methods given above to estimate how much extra clearance you have.

But you won't know for sure until you actually mount them up.

SquidPuppet

Very true. I have the same make/model 35mm tire mounted on two different rims. One measures 31.9mm and the other 36.7. Almost 5mm. Yikes.

gsa103

If you have ~3mm clearance all around, you'll likely be unless you get perversely unlucky. 28mm tires will likely be 3-4mm wider (total) than your current tires, since you're mounting them on the same rim.

I would find an object 3-4mm thick and see if you can fit it around the fork legs, seat stays, brakes, and derailuer clamp. If it fits you're probably good.

pdlamb

Bingo.

The mail order alternative would be to buy a tire, try it (front and rear) before you go out on the road, and see if they'll accept a return if it doesn't work. The two way shipping will likely be more than the "premium" (actually list) you'd pay at the LBS.

Tim_Iowa

Get a caliper. $3 at Harbor Freight.

Measure the tire you have on the rim. The actual measurement is important, because tires rarely are exactly the size advertised.

Look at the tightest areas: fork crown, brake bridge, chainstay/BB area. How much space do you see? You can also measure these areas with the caliper; a wheel without a tire gives you a good reference of where to measure.

You want at least 1-2 mm of clearance all around the tire, so it doesn't rub when the wheel flexes.

KonaRider125

Exactly the info I wanted, it looks like 28mm tires will fit, I've got 4-5mm clearance in the closest places.

Thanks all! Conti Gaterskin 28mm hardshells on order, dirt roads here I come!

Singood

I'm also considering 700x28mm Gatorskins for my recently acquired Nashbar Carbon. Did your's work?

Thanks!
Roy