Go Back  Bike Forums > Bike Forums > Fitting Your Bike
Reload this Page >

Tire/rim size confusion

Notices
Fitting Your Bike Are you confused about how you should fit a bike to your particular body dimensions? Have you been reading, found the terms Merxx or French Fit, and don’t know what you need? Every style of riding is different- in how you fit the bike to you, and the sizing of the bike itself. It’s more than just measuring your height, reach and inseam. With the help of Bike Fitting, you’ll be able to find the right fit for your frame size, style of riding, and your particular dimensions. Here ya’ go…..the location for everything fit related.

Tire/rim size confusion

Old 02-23-14, 10:39 PM
  #1  
Gozz
Junior Member
Thread Starter
 
Join Date: Sep 2013
Location: Davis
Posts: 12

Bikes: Giant RS950

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Tire/rim size confusion

Hi guys,

First off sorry if this isn't the right section!

But let me get to it. I recently moved to a new city for college. I don't have a car and my road bike is all I have to move around (so having it working very important to me).

I'm 6'4 and about 195lbs. I run 700x23c tires and recently I've been getting pinch flats like crazy!
I understand that a pinch flat is possible due to incorrect pressure in the tire, but this has been left me stranded more than once and it's getting on my nerves.

Basically I want to know if my weight is incorrect for my tires. I've been thinking about blowing like $100 for Continental Gatorskin tires (and honestly I don't want to, college student!).
Would getting these tires help me not get pinch flats or is simply because the air in the tires escapes? In that case is it because of my weight? Can I get a thicker tire and keep the same rim?

Any advice?

Thanks guys

EDIT: Maybe it will help if it adds what tires I have now. I have Vittoria Rubino Pro Slicks.

Last edited by Gozz; 02-23-14 at 10:51 PM.
Gozz is offline  
Old 02-23-14, 11:56 PM
  #2  
xjustice09x
Senior Member
 
Join Date: Sep 2010
Posts: 345

Bikes: 2012 BMC SLR01, 2012 Yeti ASR5, 2013 Trek Crockett

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
What pressure are you inflating your tires to? Vittorias recommended tire pressure for someone with your weight is 125 to 135 psi with the front tire about 5 psi lower than the rear.

Pinch flats are usually from too little air pressure. I would try increasing the air pressure. If you are already at the max rated pressure for your tire you may want to think about getting wider tires. With wider tires you can run lower pressures. An added benefit of lower pressures are a more comfortable ride. If you have a typical road bike you probably could run 25's with no problems or maybe even a 28 if there is room.

Switching tire models probably wont fix your pinch flat problem. Its all about finding out what pressure you can run while minimizing pinch flats.
xjustice09x is offline  
Old 02-24-14, 12:29 AM
  #3  
prathmann
Senior Member
 
Join Date: Nov 2008
Location: Bay Area, Calif.
Posts: 7,239
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 659 Post(s)
Likes: 0
Liked 3 Times in 2 Posts
Doubtful that Gatorskins would be any more immune to pinch flats. As mentioned, these are the result of insufficient tire pressure for the load on the tire and the road conditions (potholes, etc.). Skinny, 23mm, tires with a heavy load on them require very high tire pressure and will need to have the pressure checked frequently (preferably daily) since air slowly diffuses through rubber tubes and with the high pressure and small volume of skinny tires there can be significant losses in a day or two.

I'd keep using your current tires but keep them inflated to at least the maximum pressure listed on the sidewall (and this pressure should have a wide safety margin so going a bit higher is usually fine too). Once your current tires wear out you might consider getting some wider ones. 25mm or 28mm will be fine with your current rims, but make sure there's enough clearance for them where your tires go through the brake arms and parts of the bike frame.
prathmann is offline  
Old 02-24-14, 01:19 AM
  #4  
Gozz
Junior Member
Thread Starter
 
Join Date: Sep 2013
Location: Davis
Posts: 12

Bikes: Giant RS950

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Thanks for your replies.

It makes sense that my tires have too little pressure, I mean I alone weigh 190ish, and then I have my backpack on me..
I think I need wider tires then. My tires say they have a max psi of 120 as it is, I'm kinda scared to go over that.

I could try inflating them to the max psi and seeing how I do with that.
But I do think that the tires are getting old.
When is a good time to get them changed? I mean the tires are completely bald already.

Do you think my best bet is to just get a pump and pressure gauge then and keep the tires topped off every like 2 days?

Thanks again.
Gozz is offline  
Old 02-24-14, 01:28 AM
  #5  
FlatSix911
Senior Member
 
FlatSix911's Avatar
 
Join Date: Jun 2009
Location: Los Altos, CA
Posts: 1,774
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked 3 Times in 2 Posts
Wider tires are the way to go ... check to see if you can fit 25mm or 28mm tires.
You can run much lower pressures and will not get pinch flats from your rims.
FlatSix911 is offline  
Old 02-24-14, 12:14 PM
  #6  
Gozz
Junior Member
Thread Starter
 
Join Date: Sep 2013
Location: Davis
Posts: 12

Bikes: Giant RS950

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by FlatSix911 View Post
Wider tires are the way to go ... check to see if you can fit 25mm or 28mm tires.
You can run much lower pressures and will not get pinch flats from your rims.

How can I find out what sizes my rim can support?

Will going from 23, to say, a 25 or 28 be a huge difference in speed? Are there any tires you guys recommend that are thicker but won't drag me down too much?

Thanks

Last edited by Gozz; 02-24-14 at 01:38 PM.
Gozz is offline  
Old 02-24-14, 02:00 PM
  #7  
cderalow
Senior Member
 
cderalow's Avatar
 
Join Date: Sep 2012
Location: Potomac, MD
Posts: 776

Bikes: 2012 GT Transeo 3 2014 Cannondale CAAD 10 105

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
the issue isn't just what size your rims can support. It's what size fit through the important narrow points: brakes/frame

In all likeliness, 28c is the widest your rim will be able to go, but your frame might only be able to take 25c.
cderalow is offline  
Old 02-24-14, 02:04 PM
  #8  
Gozz
Junior Member
Thread Starter
 
Join Date: Sep 2013
Location: Davis
Posts: 12

Bikes: Giant RS950

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by cderalow View Post
the issue isn't just what size your rims can support. It's what size fit through the important narrow points: brakes/frame

In all likeliness, 28c is the widest your rim will be able to go, but your frame might only be able to take 25c.
Oh shoot! I see now..

Well then the next question then is how can I know what size tire my frame can support?
I bought the bike used, it's pretty old, I know nothing about it really.
Gozz is offline  
Old 02-24-14, 02:23 PM
  #9  
cderalow
Senior Member
 
cderalow's Avatar
 
Join Date: Sep 2012
Location: Potomac, MD
Posts: 776

Bikes: 2012 GT Transeo 3 2014 Cannondale CAAD 10 105

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Gozz View Post
Oh shoot! I see now..

Well then the next question then is how can I know what size tire my frame can support?
I bought the bike used, it's pretty old, I know nothing about it really.

the only realistic way is to measure at the typical narrow points and take that measurement and physically measure a tire.

not all tires are equal even among the same size.
cderalow is offline  
Old 02-24-14, 03:18 PM
  #10  
FlatSix911
Senior Member
 
FlatSix911's Avatar
 
Join Date: Jun 2009
Location: Los Altos, CA
Posts: 1,774
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked 3 Times in 2 Posts
Originally Posted by Gozz View Post
How can I find out what sizes my rim can support?
What tires do you guys recommend?
You current rim will support 23/25/28mm tires. The key factor is will your brake caliper and frame allow clearance.
Just measure the minimum width of the front fork and the rear chain stay to determine the maximum tire size.
Most bikes allow plenty of room for wider tires, however a few racing bikes limit you sizes.

Last edited by FlatSix911; 02-24-14 at 08:40 PM.
FlatSix911 is offline  
Old 02-24-14, 03:32 PM
  #11  
Gozz
Junior Member
Thread Starter
 
Join Date: Sep 2013
Location: Davis
Posts: 12

Bikes: Giant RS950

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by FlatSix911 View Post
You current rim will support 23/25/28mm tires. The key factor is will your brake caliper and frame allow clearance.
Just measure the minimum width of the front fork and the rear chain stay to determine the maximum tire size.
Most bikes allow plenty of room for wider tires, however a few racing bikes limit you sizes.
Ok great! The only thing I'm worried about is the width of the tire in between my brakes. Do you think if the space between there is over 28mm then I should be ok to get 28s?
I'm sure in the other areas it has enough clearance though.
Gozz is offline  
Old 02-24-14, 08:29 PM
  #12  
xjustice09x
Senior Member
 
Join Date: Sep 2010
Posts: 345

Bikes: 2012 BMC SLR01, 2012 Yeti ASR5, 2013 Trek Crockett

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
You need to look at what part of your frame has the least clearance. It will differ depending on the frame.

On my old road bike I couldn't use Continental 25's in the front because the top of the tire would slightly rub the top of the fork. On my cyclocross bike I am limited by the clearance by the right chainstay.

Also don't forget to check your brakes. There is a limit to how wide a tire will fit between the pads without deflating the tire a little bit.

There is no simple way to guarantee what tires will fit. Sizing isn't exactly standard. Some models of tire tend to run larger than the size printed on the size, while other models may be on the narrow size. Also rims come in different widths, and the shape of the tire will differ slightly depending on the rim width.

If you have 28mm clearance I would try 25's so you have little wiggle room in case your wheels ever go out of true. If there is still plenty of room with 25's then consider 28's.

If you still can't figure it out it might be helpful to post some pictures so we can see how much clearance there currently is. You can also take it to a bike shop and they should be able to help you find an appropriate tire.
xjustice09x is offline  
Old 02-24-14, 08:42 PM
  #13  
FlatSix911
Senior Member
 
FlatSix911's Avatar
 
Join Date: Jun 2009
Location: Los Altos, CA
Posts: 1,774
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked 3 Times in 2 Posts
Originally Posted by Gozz View Post
Ok great! The only thing I'm worried about is the width of the tire in between my brakes. Do you think if the space between there is over 28mm then I should be ok to get 28s? I'm sure in the other areas it has enough clearance though.
Measure between the calipers and don't forget to open the quick release lever shown in the photo.

FlatSix911 is offline  
Old 02-24-14, 09:49 PM
  #14  
Gozz
Junior Member
Thread Starter
 
Join Date: Sep 2013
Location: Davis
Posts: 12

Bikes: Giant RS950

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I'm just getting confused because I'm thinking about measuring between the brake pads instead of the whole caliper.
Here's a picture I just took. Let me know if it helps. If not I'll try something better!

The measurement is in cm by the way not mm!

Attached Images
File Type: jpg
20140224_194411.jpg (96.7 KB, 28 views)
Gozz is offline  
Old 02-24-14, 10:59 PM
  #15  
FlatSix911
Senior Member
 
FlatSix911's Avatar
 
Join Date: Jun 2009
Location: Los Altos, CA
Posts: 1,774
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked 3 Times in 2 Posts
Originally Posted by Gozz View Post
I'm just getting confused because I'm thinking about measuring between the brake pads instead of the whole caliper.
Here's a picture I just took. Let me know if it helps. If not I'll try something better! The measurement is in cm by the way not mm!

You are making good progress here... with a measured 25mm brake caliper clearance.
Now check to see if you have a small release lever to open the brake caliper wider to say 35mm.
Then take a look at this article and it will explain in detail how to choose a tire width for you bike.

https://www.slowtwitch.com/Products/T...idth_4026.html

FlatSix911 is offline  
Old 02-24-14, 11:09 PM
  #16  
NZier
Senior Member
 
Join Date: Jul 2012
Location: Lee's Summit, MO
Posts: 90

Bikes: 2011 Cannondale Carbon Synapse (Ultegra 6800 11-spd), 2009 Blue CXC, 1979 Univega Gran Turismo

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Here's my perspective on pinch flats. They shouldn't happen. Pinch flats are most often that the tube is improperly placed. I weigh 230-250 lbs (depends what part of riding season it is, and right now I just recovered from ACL reconstruction). I've never had a problem with pinches. I've run 23s, cheap and expensive, 25s, and ridden rushed limestone on road tires... all inflated to around 100 PSI.

What kind of roads are you riding? What kind of wheels? Have you examined the wheels for dents/cracks? I'm riding a set of SR-2 stock Giant (read cheap) wheels...

Maybe I'm just offended that you're considering 190lbs an "extreme weight" for a tire or wheelset. Take this over to the Clyde forum and some people will laugh at you. I usually run Serfas 25s; they're cheap, but they've been great for me (at 240lbs)
NZier is offline  
Old 02-24-14, 11:31 PM
  #17  
Gozz
Junior Member
Thread Starter
 
Join Date: Sep 2013
Location: Davis
Posts: 12

Bikes: Giant RS950

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by FlatSix911 View Post
You are making good progress here... with a measured 25mm brake caliper clearance.
Now check to see if you have a small release lever to open the brake caliper wider to say 35mm.
Then take a look at this article and it will explain in detail how to choose a tire width for you bike.
Thanks FlatSix911.
I think that's as open as my caliper gets though, I moved the lever and it doesn't open or close too drastically.
It's an old bike and that part could be breaking.
Gozz is offline  
Old 02-25-14, 01:29 AM
  #18  
prathmann
Senior Member
 
Join Date: Nov 2008
Location: Bay Area, Calif.
Posts: 7,239
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 659 Post(s)
Likes: 0
Liked 3 Times in 2 Posts
Originally Posted by Gozz View Post
Thanks FlatSix911.
I think that's as open as my caliper gets though, I moved the lever and it doesn't open or close too drastically.
It's an old bike and that part could be breaking.
The distance between the brake pads is irrelevant - that's determined by how wide your rim is and you won't be changing the rim. What counts is how much space there is between your current 23mm wide tires and the parts of the bike that currently come closest to touching the sidewalls or tread of the tire - that could be either parts of the brake arms, the front fork (esp. the bottom of the crown), rear stays, or seat tube. In principle if you're going from 23mm to 25mm you should only need one mm of clearance since increasing the diameter by 2mm will increase the radius by only 1mm. But tires vary in their actual dimensions so I'd look for at least a couple mm clearance of your current tires before going up a size. To go from 23mm to 28mm should only require 2.5mm (1/10") of clearance, but again I'd want a little margin in case the tire you buy is on the large side. If you have about 4mm of clearance with your current 23mm tires then most nominal 28 mm tires should be ok.
prathmann is offline  
Old 02-25-14, 02:13 AM
  #19  
Gozz
Junior Member
Thread Starter
 
Join Date: Sep 2013
Location: Davis
Posts: 12

Bikes: Giant RS950

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Ok I think I get it, thanks prathmann!
I should be fine to get 28s then (hopefully).

Now the question becomes what tire should I get?
I've been looking around and I've seen a few that don't break the bank (I only ride to school and back, no racing, etc.)
CST Caldera, Vittoria Zaffiro II, Vittoria Rubino III are some that I found. Are these any good?

Also is it ok to ride with a 23 on the front and a 28 on the back as well as being completely different tires?
Gozz is offline  
Old 02-25-14, 02:33 AM
  #20  
hamster
Senior Member
 
Join Date: Apr 2006
Location: Escondido, CA
Posts: 2,240
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Aside from considering getting wider tires, I would recommend two things:

* More expensive tubes. Seriously, savings from going with cheap tubes are often more than cancelled by their lack of longevity. I often see cheap tubes blow along the seam because they are poorly welded/glued there.
* Brush up on your tube installation techniques. Watch some youtube videos. There is a difference between simply getting the tube into the tire and doing it right. If you don't do it right, chances of a pinch flat are exponentially increased. If you ever blew a tube while installing it (while fixing a flat), you're not doing it correctly.
hamster is offline  
Old 02-25-14, 05:17 PM
  #21  
Gozz
Junior Member
Thread Starter
 
Join Date: Sep 2013
Location: Davis
Posts: 12

Bikes: Giant RS950

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by hamster View Post
Aside from considering getting wider tires, I would recommend two things:

* More expensive tubes. Seriously, savings from going with cheap tubes are often more than cancelled by their lack of longevity. I often see cheap tubes blow along the seam because they are poorly welded/glued there.
Ah that does make sense! What are better tubes? What brands I should say.

Any recommended tires that don't break the bank?
Gozz is offline  
Old 02-25-14, 08:05 PM
  #22  
hamster
Senior Member
 
Join Date: Apr 2006
Location: Escondido, CA
Posts: 2,240
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Gozz View Post
Ah that does make sense! What are better tubes? What brands I should say.

Any recommended tires that don't break the bank?
You usually can't go wrong with Continental, Michelin, Vittoria. I prefer the ones with threaded valves, they are easier to inflate and it's one less place to damage the tube while installing it.
hamster is offline  
Old 02-25-14, 08:26 PM
  #23  
FlatSix911
Senior Member
 
FlatSix911's Avatar
 
Join Date: Jun 2009
Location: Los Altos, CA
Posts: 1,774
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked 3 Times in 2 Posts
Originally Posted by Gozz View Post
Ah that does make sense! What are better tubes? What brands I should say.
Any recommended tires that don't break the bank?
Check out https://www.biketiresdirect.com/tires-and-tubes-category
I would recommend starting with Continental City/Touring tires and tubes.
FlatSix911 is offline  
Old 02-25-14, 08:43 PM
  #24  
Gozz
Junior Member
Thread Starter
 
Join Date: Sep 2013
Location: Davis
Posts: 12

Bikes: Giant RS950

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by hamster View Post
You usually can't go wrong with Continental, Michelin, Vittoria. I prefer the ones with threaded valves, they are easier to inflate and it's one less place to damage the tube while installing it.
Originally Posted by FlatSix911 View Post
Check out https://www.biketiresdirect.com/tires-and-tubes-category
I would recommend starting with Continental City/Touring tires and tubes.
Thanks you guys guys are super helpful!
I'll check out some tubes and tires.

I just have 1 last question.
Is it ok to run a bigger tire on the back than on the front?
My front tire is fine but it's 700x23, the back tire I'm looking at is 700x28.

Will anything even change?

Thanks again guys
Gozz is offline  
Old 02-25-14, 11:19 PM
  #25  
xjustice09x
Senior Member
 
Join Date: Sep 2010
Posts: 345

Bikes: 2012 BMC SLR01, 2012 Yeti ASR5, 2013 Trek Crockett

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Gozz View Post

I just have 1 last question.
Is it ok to run a bigger tire on the back than on the front?
My front tire is fine but it's 700x23, the back tire I'm looking at is 700x28.

Will anything even change?
You can mismatch the sizes if you want. Continental sells the attack/force set with 700x22 front and 700x24 rear. I used to run 700x25 rear and 700x24 front because thats the largest my frame would fit.

Other than the rear of your bike sitting a few mm higher than it was before, it shouldn't change much. At the proper pressure the wider tire should be more comfortable over bumps.
xjustice09x is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.