BartmanJ

I want to install a more agressive tread on my hybrid because I am spending half the time off paved roads. Considering knobby and cyclocross...

Need to find out the ACTUAL width of tires installed on 700x622 rims so I can be sure of fit within the chain stays. (I am in Saudi Arabia, so LBS not available)

What is the real width of 700x38, 700x40, and 700x42 tires on these rims?

In a previous query, one respondent indicated a 40 actually resulted in almost 44 with...With your info / guidance, I can order the correct size. If you might have other suggestions, please offer!

Ever grateful!!

400trix

To be slightly flippant, unless the surface is really loose, slicks work just fine on dirt.

Now, to answer your question, read this.

FastJake

Depends which tire you use, and to some extent what the width of the rim is. I've rarely seen a tire measure wide, usually they are narrower than listed. I've had 40mm tires measure 35mm, and 50mm tires measure 45mm.

Bottom line, you don't know if it will fit until you try it. Even if you try measuring your frame. It's really tricky trying to guess where the tire will sit, and even more difficult trying to guess how tall it will be and whether it will run out of room in the vertical direction (I've had that happen..)

+1 Slicks aren't bad in a lot of "offroad" conditions. If you ride half on half off I would definitely go for a slick in the back. Maybe a mildly knobby tire up front. Knobby tires on pavement just drive me crazy.

Andrew R Stewart 

Actual dimensions are actually measured. Too many variables to give you a black/white answer. Since tire width labels are just that, a label and not a real dimension and rims have differing internal widths for the same diameter one has to mount, inflate and measure. At best you'll get approximate widths otherwise. Andy.

fietsbob

The rim spread. width that the beads are apart, effects the profile m contact patch of the tire.

Then there is carcass design

the Nokian A10 is quite squared off, WTB Allterrainasaurus , somewhat similar,

Continental Travel contact is a past the end of the pavement touring tire.. only 37 width in 700c

just 1 size in the 26" ones too.

BartmanJ

Many thanks for the link - VERY informative and helpful!!

FBinNY 

To get the true width you need to know the true circumference, or a good close approximation.

The circumference is the bead to bead width of the tire laid flat (a spec I wish tire companies would offer) + the inside rim width. Since the same tire can be mounted on various width rims the tire maker cannot be certain of final width for their tires.

Once you have the circumference, divide by Pi to get width.

This will only be a good approximation, because factors like how much the tread crown wraps around the side can alter it, but it is a reliable comparative predictor of comparative widths within 1-2mm.

Since logistics are a big factor, you might ask the seller or a forum member to lay flat and measure the bead-to-bead width of a particular tire you have in mind before buying.

HillRider

A minor detail but "700x622" is saying the same thing twice. What is commonly known as a 700c rim is more accurately given as an ISO 622 which means the bead seat diameter is 622 mm. That says nothing about the width between the rim's flanges which has a large effect on installed tire width and, indeed, on what width tires are suitable.

A tire installed on a wide rim will measure wider across than the same tire installed on a narrower rim.

ksisler

BM; This is a meaning of life type question. No immediate answers as tires are not factual items. To get this right you need to do a few things to help with the analysis;

1) With a pair of wheels and tires in the frame and put a small bit of masking tape on the left chainstay and on one of the folk blades ... stick it on where the current tire is the fattest. They carefully put a mark on the tape where the tire is fattest... try to be accurate.
2) Remove the wheels
3) Measure the gap between the chainstays right where your mark is. If you don't have a set of inside calipers, then just take a post card or similar and trim it down a millimeter at a time until it just slides in between the stays right where you marked it.
4) Measure the "card tool" with a good ruler and write on it "Rear, XXmm's"
5) Repeat for the fork to yield you second card tool "Front, XXmm's"
6) Figure out which model, brand and drilling your rims are and write that down. You may have to take a tire off.
7) Measure the width of the rim on the outside where brakepads would hit the rim and the inside where the tires would set. You want to see on your notepad something like this:
"700C, 36-spoke, Mavic, Model 345b, 26mm/22mm"
8) Scratch out your description, such as:
"I am going to be riding on XXX surface. My Total rider + bike + accessories weight is YY KG's or pounds. My riding style is Downhill/MTB/Touring/racing, etc. I ride agressive/casual/etc."

Now post all that to the forum and ask the question: "Guys; give this, what are some recommended tires based on actual experience that will fit likely my stuff and style? Thanks //OP2

Hope that helps
/K

pierce

on my hybrid, which has 25mm wide (outer) 700c rims, a 700x35 Nimbus was in fact just about exactly 35mm wide, and a 700x32 Vittoria Randonneur Hyper is just about exactly 32mm wide.

you didn't give your rim width, so we can't compare with your situation.

before pushing it TOO close, remember wheels flex under load, so even if it looks like it will squeak past the chainstays at rest, if you're cranking on it, it could still rub.