i would not focus on running a larger tire because it says its larger , but take measurements of your rim and internal width , to run a 28 you need at least a 17mm internal , other wise i fell you wont see much benefit , you could also run a 23 on a rim with 20 to 22 mm internal width and get a tire that measures from 26mm to 28 depending on the tire , and you will get the size with less weight penalty , and maybe an aero and cornering boost as well !

The rims are Fir 2000. I measured the internal width of the rim at 13mm. Again I will go with 25mm tires and see how it does. It now seems likely that 28mm would have had clearance problems on the frame aside from the rim fit question.

That's fine, thread has provided good entertainment!

Do you have calipers that you can measure your current clearance?

I stated in my original post that I have no experience in dealing with tire size swaps This is why I started the thread in the first place.. Initially I measured clearance with a calipers for the brake pad width and can do the 28mm. I did not consider the tire would grow in circumference as well. Please Forgive the ignorance of a novice...
After reading so many kind responses about tires and brake bridge and fork interference I realize I might have been too optimistic in the first place.
Does a bigger tire grow in height and width in the same numbers?

Larger size will be larger in both dimensions but you can't generalize how much. It will depend on the specific tire and rim combo.:thumb: IME, the fork crown and chainstays are usually where you will have issues with older bikes.

It is hard to predict. Different tire have different profiles. Some are taller than others. Also rim width affects the hieght but not by a whole lot, until you get to really wide rims. Best thing to do if you want to know is ask someone with a particular tire to measure the hieght from the edge of the rim.

Also not true. Moving up from 25mm to 28mm tires on my old Bianchi yielded a noticeable benefit in comfort, with no drawbacks in speed or handling. Rims are still what came on it in 1991.

I personally have no interest in ever running a tire smaller than 28mm on any bike if clearance allows. :thumb:

The tire will get ‘taller’ as the size gets bigger, generally ​​​​​​ by the same amount it gets wider. How much exactly depends on the make and model of the tire, and the specific rim you’re mounting it on.
Also, if you’re going from a slick ‘racing’ tire, to a commuter/touring tire with a built-up tread, it’ll be taller, as well, even if the nominal size is the same.

I wouldn’t get hung up on the rim width. All it means is that the tire profile will be more ‘lightbulb’ than ‘horseshoe’ As it’s been mentioned, MTBs have run much, much wider tires on the same size rims for a long time.

As far as what fits on your bike, I wouldn’t be surprised if it only takes 25mm. It’s just that that was the fashion for sporty road bikes in the 1990s; skinny tires and tight clearances.
That was the boom era for MTBs and about the time of the rise of the flat-bar hybrid, so road bikes tended to be targeted to the ‘racer’ set.

My wife has a Bianchi road bike of that era. It came with 23mm tires. I mounted 25s on it and it fits, but is a PITA if you want the brakes to be close to the rim, since the brake caliper QRs do not open enough for the inflated tire to slip right through. As it also has horizontal dropouts it is more difficult removing the rear wheel. I tried the front wheel of my bike with 28s and it will fit between the fork blades, but absolutely will not clear the crown or brake bridge.

Well as I said... “IF it fits...” From the comments here, sounds like it won’t.

That’s a shame. A frame that could not clear a 28 would be out the door in my stable.

My Fenix currently has Fulcrum Racing 5 wheels and Conti 4000 25mm tires. When it is time for new tires I will stay with Conti but the newer 5000 GP. What are the advantages of 25mm to 28mm? If they make the ride more comfortable then I am all for it.

My Battaglin has some of the tightest geometry I have ever seen, and there's no way you'd ever be able to fit anything larger than a 23 mm tire in the back, you'd hit the seat tube! It's got vertical dropouts, so there's only one place you can put the rear wheel.

Still, I'm keeping it, I don't care if it won't do gravel. There should always be a place in every road bike stable for a no-compromise, smooth-roads-only, steep-angled, "twitchy" (it's not) classic steel race machine.


https://cimg1.ibsrv.net/gimg/bikefor...4648be92a2.jpg

That’s cool. Beautiful bike.

In our stable of 3, she is happy with it.

I was the one who wanted her to try 25s or 28s, primarily to make it easier to get tires locally when we got back into regular riding or were on the road. The 25s are fine with her, and we do minimal gravel (at least intentionally :) ). She likes a classic diamond frame drop bar bike and is NOT a fan of the matte paints or black components that are now the fashion. Her comment to bigger tires was if she wanted fatter tires, she would ride the 1973 Peugeot, which she surrendered reluctantly (at my request and offer to buy her a new bike of her choice) to avoid French parts and threading. That frame has the room for 32s (27") and if we went for hook bead 700C rims could probably fit 35s, but why? I have ridden 28s and 1 1/8 tires long before the fatter supple tire benefits became popular, and moved up to Rene Herse (Compass) 28s and now 32s and am curious about their 35s with the Endurance casing.

When the day comes that we can no longer ride, the Peugeot will be wall art in the rec room, along with my early 1960s Telecaster guitar.