I have been mountain biking for a long time now and several times have successfully used tyres bigger than the recommended size for the rim. So my question is: how much bigger can you go with 700c wheels (which i am new to)? Whats the biggest tyre youve ever squeezed in there and got away with? My rim is 700/18-23.

Cheers.

The question you should be asking (which is asked here all too often)...is how big of tires will fit in your frame?

Yeah, and sometimes your brakes will the limiting factor. I suppose there is too big a tire for any given rim, but I haven't hit it yet. I am currently running 32c tires on Open Pro rims (19 width?) on a bike I picked up to run 37c Continental ice tires (using the same rims). I hear it is "better" to be riding wider rims, especially at low pressures and for wind resistance. (I will need real help with that high speed aero drag when I use those sticky ice tires! Yeah, right!) I find cornering works just fine with those skinny rims so I don't sweat it.

Ben

So you think frame clearance is the limiting factor? Ah well, thats easy then, got plenty of frame and fork clearance. ill see how i get on with my 23s and maybe try something bigger if they dont like these cracked up roads i ride on.
Thanks

Ah yes brakes as well, obviously. Didnt think of that cos the brakes arent on the frame yet so i sort of forgot about them.

What are "brakes"?

It is often hard for me to tell if Scrodzilla is being serious or snarky, but I was not thinking about brakes either

Out of curiosity...what frame are you using that you have no concern about tire clearance?

Its when the commercials are shown

Ive been waiting for this question. Its a 1950s Elswick-Hopper Whirlwind. Im building it up as a go to work/have some fun/try fixie-ing bike....

Just tried uploading a pic but cant for some reason. will try again later.

Do you know what you have there? Done any research on it? Got any of the old bits? Likely before Raleigh or Falcon grabbed them up so could be pretty interesting old bike - if in any kind of decent shape & you don't eff it up.

I'd (& hopefully others) like to see pics & maybe you should check in with the C&V sub-forum before you do any more damage...

Yeah i did some research on the company, but cant find much on the model though i know it was built just over the river from where i live. it came just as frame and forks with headset bottom bracket and seat tube. maybe ill pop across there and see what they think of it.

Tire Sizing Systems

About 3/4 down the page is the chart you want.

Thanks man

As a side note, the typo in the title of this thread is annoying me.

make sure to measure, i got 32's for a fork that could fit 38's without a brake, but with the brake i could maybe get 28s in

seeing as its such an old bike, it most likely has miles of clearance. i have an 87 fuji i could prolly get 40s into without the fenders

An older 27" road bike frame will fit pretty much any 700c tire.

You'll be able to put 42s on your 23 rims, but the ride is going to suck, I think they call it "fold over" or "roll over". Basically you have no stability in corners because of the balloony shape of the tire squeezed onto a smaller rim.

Thanks for the replies guys, still cant upload an attachment, anyone know why that might be?

General rule of thumb is 1.5-2.0 x inner rim width. I have some 32 tires on 17 rims and it's OK. But you are right, exaggerated light bulb shape will make them feel really weird.

Stu2. FYI, be sure to check for vertical clearance too. I measured a fork once to make sure 35mm tires would fit and there was plenty of width, all the way to the top. When I tried to put the finished wheel into the fork, it was about 3mms too tall. Ooooops. It was an easy fix though, since I caught it before painting.

generally you can go up 2-5mm on a bike that is designed for fenders (if you don't use fenders).


It depends on the frame, but I have been limited by:
- front derailer motion
- brake mounting point (I have dremmeled brakes, or just taken them off for a FG
- on my road bikes, the width of the brake calipers usually can't be 28mm or the tire will have to be deflated to get them inside the calipers.
- often a slightly bigger tire can be put on the front fork than on the rear - this will give you a little bit more cush up front.


Also, most people should be riding their tires at the minimum pressure on the sidewall. According to detailed testing, there is very very little difference in rolling resistance until you get below a critical point. You can also go 10% less pressure in the front tire since the back tire takes about 50% more weight than the rear wheel

realistically, you can put just about any tire on any rim. I've put 47mm tires on 17mm rims, no problem. The real problem is that you can't run low pressure or you will get some squirm. But if you have enough air in the tire, you are not going to have any issues.

the photo is likely too big i think the limit is only 2mb. try dropping the quality of the photo a bit.