Ok so I have a rim that has 19mm outer width and 13.6mm inner width. By sheldons page that puts me at the upper limit of size 25mm wide tires but he says this is conservative.
What size tire can I realistically put on this rim without safety/special maintenance concerns?

its a 700c rim if it matters.

23 with no problems at all.
I'm running Mavic Open Pros, and they're wider than 19mm, but 23 wide Bontrager tires work great.
I think 21s would be fine too, as long as you keep them inflated to a high PSI.

Im mostly trying to figure out the widest tire i can fit. I like wide tires (wide being in the 700x38 range)

i have the same size and i have about 300 miles on a set of 28mm wide michelin city tires with no problem.

Cyclocross guys run the same rims I do, and they've got 700x30-35 tires.
As long as the rim isn't super light, or you pump the tires to a pointlessly high pressure, you should be fine.
The big limiting factor is clearance at the fork/brake.

I wouldn't hesitate to run 35-38s on those rims. I run 40s on 22mm (outside) rims, and they're on my MTB, stock tires are 58mm wide.

Same rim size, 28mm no problem. I've got 34mm tires on some open pros and mavic's 'max' tire size is something silly like 28mm. As long as they are properly inflated, no problems.

I have run up to 40s on my 16mm wide rims and had no problems whatsoever.
I am familiar with the tire sizing guidelines given by Sheldon brown but IMHO they are very very conservative.

Yeah, I'd try it to see first. I run a 38mm tire on a 15mm inner width and have no problems at all.

Make sure your brake pads retract and dont rub on the tire and you're fine.

Thats crazy, i really wasnt expecting such a huge range but I can say that it makes me happy

The one issue you might have when running a wider tire on a narrower rim is the tire will take on a different shape. Chances are it will bulge outwards giving it a more rounded profile. This isn't a major issue, but it does change cornering characteristics, and makes it harder to get out of the brake. If you can live with that, you're golden.

so am i worried about the tire clearing the fork, sideways or vertically?
I am actually switching from 27" wheels to 700c so vertically shouldnt be an issue

Most of the 27" frames had wider clearances all around, but just stick a ruler across the rim at both stays to check your available width.

sheldon brown's website has a chart on rim/tire fitment. It's worth to references it just to make sure....

I'd put some 25's on it unless you plan to go off-road.

Al

I like to put large tires (~32mm) on my long distance commuter bikes.

Hey, it's totally up to you. But on pavement you'd make that long distance in less time on 25's.

the time saved will be negligble and he will greatly impove the ride...OP I run 35 Racing Ralphs on the same size rim

Agreed. Actually, it is debatably whether narrow tires actually make a bike faster in many conditions... if a wider tire and a narrower tire are inflated to the same pressure, the wider tire will have slightly less rolling resistance! Of course, this is probably because the wider tire inflated to the same pressure as a narrow tire is probably overinflated, but that means that a wider tire can be run a lower pressure than a narrow tire and have the same rolling resistance!!!! Rolling resistance is cause by deflection in the casing and sidewall of the tire, and a wider tire will have less deflection. Just make sure you have some good fast rolling tires. (Sadly, in general, the best hand-made low-rolling resistance high TPI count tires are only made in narrow versions because it is what racers usually use due to lighter weight)

Here's the deal.

When I did what you are thinking about I found that at 30c I couldn't keep the tires as soft as I like
without the rear wheel jumping around in corners. Btw, I am a big guy, so if you are under 200, this
might not apply so much. I also like to keep the tires as soft as I can without creating other problems.

28c is a great size for a lot of people. I ran Rivendell Ruffy Tuffys for years and loved them. Then the roads
around here turned to crap.

Lots of good tires in that size. Vittoria has a couple new tires, the Randonneur Hyper and Pro. I am planning on trying the Hyper
this year, but in the 35c size.

Do you have data to back that up. According to test run by Jobst Brandt it is not true. These tests were run on sizes between 20 mm and 28 mm and show that a narrower tire at an equivalent pressure has less rolling resistance: https://yarchive.net/bike/rolling_resistance.html.
A wider heavier tire will accelerate more slowly and climb more slowly. These tests also show that rolling resistance is lower with higher pressure.

Ok, what do you mean jumping around? That sounds unnerving.
Furthermore, how low are you talking about on a 700x30 ? like 60 psi?

No it's not debatble.

Otherwise everyone who races would be riding "wider tires". If what you say is true, there'd be a huge demand for high TPI, wide 25+ tyres that every tyre manufacturer out there seems to ignore.

Why stop at 25? Why not slap on 40mm+ tyres on every race bike and claim it's faster? Surely you're not the first person to claim this.

Give me a break

I don't deny that a heavier tire will accelerate and climb more slowly... I was talking about rolling resitance.

ANd what the chart in the article is comparing is high TPI tires with low TPI tires... there is no direct comparison between identical tires with identical TPI counts of different widths... from what I can see.

Operator, I'm sorry your mother never loved you, but I don't blame her.

From Sheldon Brown's article on tyres:

"The short answer to this question is that, yes, a wider tyre of similar construction will have lower rolling resistance than a narrower one at the same pressure."


Perhaps there is more to a tire than rolling resitance. Perhaps a wider tire is heavier. Perhaps a wider tire increases aerodynamic resistance. I guess I misspoke. The tire is not necesarily faster, but may have lower rolling resistance.

Perhaps I should have said that "if a wider tire and a narrower tire are inflated to the same pressure, the wider tire will have slightly less rolling resistance!" Oh, wait. That is what I said.