# max tire size w/ ultegra brakes & vista wheelset?



## logbiter (Sep 14, 2005)

First off, roadbikes are new to me (longtime offroad cyclist & mtbr.com member).

I'm putting together a road ride (fuji finest steel frame I got for a reasonable deal) w/ some ultegra calipers & an easton velomax vista wheelset and am wondering how wide of a touring type tires I might be able to fit? 
It's my understanding that the calipers will be a limit as well as the frame, hence my query here. Since the frame deosn't have canti stops, that's not an option.

I'm hoping to get a bit more cushion & pinch flat protection from something like a 700x30-35 tire for my currently 200+ lb clyde status. 

Thanks,
S


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## moose8500 (Jun 18, 2005)

I really doubt you can get a 30 and above in there....


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## logbiter (Sep 14, 2005)

moose8500 said:


> I really doubt you can get a 30 and above in there....


so, I guess I'll shoot for a 28, at least that's a bit more volume than a 23. Are some tires known to have more volume than others?

mostly due to lack of height on the calipers brakes, I'm assuming?

thanks


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## Kerry Irons (Feb 25, 2002)

*Frame & fork, not brakes*

As a general rule, it is your frame/fork that limits tire size, not the brakes. The brake's "lowest" point is even with the bottom of the fork or the bottom of the rear brake bridge. What size tire will fit depends on your specific frame and fork. Put wheels in the frame and measure the clearance. This will tell you how large a tire will fit.


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## MR_GRUMPY (Aug 21, 2002)

Different frame makers leave different amounts of room for tires. Two friends Waterfords are made to only fits 700X23's and sew ups. My Gunnar is made to fit up to a 700X26.
You need to look at your bike to see how much room you have for larger tires. A 700X28 tire from one maker may be different from another. If a rear tire a very "tight" in your frame, you may not be able to fully inflate it until you get it into the dropouts.


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## geraldatwork (Jul 15, 2005)

I have a similiar question. On my bike on the rear fork there is about a 3mm clearance from the top of the tire to the inside bottom of the fork. I am currently running a 700-23. For winter riding I would like to go to at least a 25 tire possibly a 28. Do larger tires only go wider or taller also? I know different tires have different profiles for example my Conti GP3000 seem a little taller than other tires and that might be part of the reason for the reduced clearance.


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## MR_GRUMPY (Aug 21, 2002)

I doubt very much if you can fit a 28 in there. For winter, try a 25, and keep it pumped up to 130.
You might loose 10 psi when the tire cools to 20 F...( I'm sure that someone can calculate exactly how much air pressure a tire loose when it goes from 70 F to 20 F )


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## Bikehigh (Aug 2, 2004)

*Fatties Fit Fine*

For what it's worth, I'm running a set of 37mm Ritchey Speedmax Comp cross tires in my Surly Steamroller with Ultegra calipers. They do fit, but as you can see there's no mud clearance, and if even a little pebble picked up by the tires gets stuck for a while. That's what I get for riding it on gravel I guess. I do get some rub when using the front brake too, but it's not really a big deal.

Also, while the tires do fit, removing the wheels from the bike requires deflating them enough to squeeze past the brake shoes, as the QR doesn't have near enough throw. Not a big deal really, but it does mean I'd rather throw the bike in the back of my pickup truck than carrying it on a tray on a roof rack. If the brake levers had a QR too, I might not have a problem. Slightly narrower tires without the side knobs would probably have no issues, but that's all conjecture. I do think that when I replace these tires though, I'll opt for 32's unstead of the 37's, but I do like them for what I use them for and they handle my 215 lb bulk very well on all kinds of terrain. Then again, 25mm slicks handle my bulk fine too. They just can't take the abuse as well.


















Here's another spot that could cause you problems with a tall tire.


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## Kerry Irons (Feb 25, 2002)

*Think about it*



geraldatwork said:


> Do larger tires only go wider or taller also?


Since tires are quite flexible, by definition they are always circular in cross section. Since the rim provides a fixed base, every 1 mm increase in tire diameter shows up as 1 mm more height, and 0.5 mm wider on each side. A simple thought experiment.


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## likeguymontag (May 31, 2003)

Kerry Irons said:


> [...] 1 mm more height, and 0.5 mm wider on each side.[...]


Makes a lot of sense. Perfect, except that it seems that manufacturers' measurements don't always match up to real life. Would that someone had accurately meausred the real-life dimensions of the tires the O.P. wants to ride.


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## SCW (Mar 19, 2005)

MR_GRUMPY said:


> I doubt very much if you can fit a 28 in there. For winter, try a 25, and keep it pumped up to 130.
> You might loose 10 psi when the tire cools to 20 F...( I'm sure that someone can calculate exactly how much air pressure a tire loose when it goes from 70 F to 20 F )



Boyle's Law, PV=NRT, P= Pressure, V= Volume, N=#moles R=constant, T=Temp. Hooray! I was able to contribute....even if it is something pretty much usless, we don't know the volume and it would be a lot faster to simply pump the stupid tire up than it is to estimate volume and # moles of air.

Back to lurking for me.....


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## Kerry Irons (Feb 25, 2002)

*Too complicated*



SCW said:


> Boyle's Law, PV=NRT, P= Pressure, V= Volume, N=#moles R=constant, T=Temp. Hooray! I was able to contribute....even if it is something pretty much usless, we don't know the volume and it would be a lot faster to simply pump the stupid tire up than it is to estimate volume and # moles of air.


Talk about making the simple complex! You just take the ratio of the absolute temperatures (in either Kelvin or Rankine) and you get the ratio of the pressures. You never need to know the volume or the number of moles, or the specific gas law contstant. So (20+460)/(70+460) = 90% - the pressure at 20F is 90% the pressure at 70 F. You lose 10 psi out of 100.


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## Bikehigh (Aug 2, 2004)

Kerry Irons said:


> Talk about making the simple complex! You just take the ratio of the absolute temperatures (in either Kelvin or Rankine) and you get the ratio of the pressures. You never need to know the volume or the number of moles, or the specific gas law contstant. So (20+460)/(70+460) = 90% - the pressure at 20F is 90% the pressure at 70 F. You lose 10 psi out of 100.


So, what does all this talk between you two about your penile implant pressure settings have to do with answering the question about max tire size with Ultegra?


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## SCW (Mar 19, 2005)

Kerry Irons said:


> Talk about making the simple complex! You just take the ratio of the absolute temperatures (in either Kelvin or Rankine) and you get the ratio of the pressures. You never need to know the volume or the number of moles, or the specific gas law contstant. So (20+460)/(70+460) = 90% - the pressure at 20F is 90% the pressure at 70 F. You lose 10 psi out of 100.



LOL, you're right of course, I'll go back to lurking, too much rain and not light long enough to ride these days, might as well discuss the inane online like everyone else


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## Kerry Irons (Feb 25, 2002)

*That's hard*



Bikehigh said:


> So, what does all this talk between you two about your penile implant pressure settings have to do with answering the question about max tire size with Ultegra?


A penile implant at 100 psi? Now that's hard


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