Tyes and Inner Tubes - What do the numbers mean??

Norry1

Guru
Location
Warwick
OK, real newbie question here, apologies but I'm trying to learn from the bottom up.

What do the various numbers and letters mean on tyres and inner tubes? What else do I need to know?

Thanks in advance.

Martin
 
This Guide by Sheldon Brown may help.
 
OP
Norry1

Norry1

Guru
Location
Warwick
HLaB said:
This Guide by Sheldon Brown may help.
Ummm - I've read it, and I don't think I'm a total cretin (half maybe) but I couldn't really follow it.

My bike has rims described as:

Alex Crosstrail, 700c, alloy double wall w/ machine sidewalls, 32h

and tyres described as:

Specialized Borough XC Sport 700x45c, 60TPI, wire bead


What does all that mean?


Martin
 
OP
Norry1

Norry1

Guru
Location
Warwick
ah brill - so does the 700 mean 700mm diameter of the wheel, or the tyre? What does the C mean?

The 32h means there are 32 spokes per wheel? What does the h mean?

The tyre is described as 700 as well - how come? What does the 45c mean?

What is tpi?

Sorry to be a nause :ohmy:

Martin
 
Norry1 said:
Ummm - I've read it, and I don't think I'm a total cretin (half maybe) but I couldn't really follow it.

My bike has rims described as:

Alex Crosstrail, 700c, alloy double wall w/ machine sidewalls, 32h

and tyres described as:

Specialized Borough XC Sport 700x45c, 60TPI, wire bead


What does all that mean?


Martin
I take it you added the latter bit after lee's answer; your tyres are 700mm diameter and 45mm wide that the important bit, 60 TPI just refers to the Threads per inch Sheldon
The higher the TPI number, the thinner and more flexible the tire fabric is. Thin-wall (high TPI) tires tend to be lighter and have lower rolling resistance, but they're more easily damaged by road hazards.
and the wire bead is just there's a wire bead around the rim of the tyre as simple as that. Some lighter and more expensive tyres don't have a wire but its not really important IMO.
 

PpPete

Guru
Location
Chandler's Ford
Tyres for "700c" rims will sometimes be described as x-622 (x in your case will be 45)

Don't expect to be able to measure precisely 700mm anywhere on a 700c tyre.
622mm on the Bead Seat diameter maybe, but 700 mm - unlikely.

That's what Sheldon's table tells you.
 
OP
Norry1

Norry1

Guru
Location
Warwick
Thanks guys - think I've got it now.

And yep, I added the tyre bit after Lee's reply - hence why my editing reason says cos I can't cut and paste properly :ohmy:

No doubt another dumb question is only just around the corner!

Martin
 

PpPete

Guru
Location
Chandler's Ford
Norry
There are no "dumb" questions.....

When I returned to cycling and found the technology had all changed since my mis-spent (and long-gone) youth I started Googling and frequently found the most useful answers within CycleChat.

Those answers were only there because other people had asked the questions.

Please keep asking the questions and help keep CycleChat the great place it is today.
 

migrantwing

Veteran
As mentioned, TPI means Threads Per Inch. (sometimes referred to as EPI - Ends Per Inch) The higher the TPI, the thinner the tyre wall and more flexibility, usually found in out and out slick race tyres. The higher the TPI, the more prone to p*******s the tyre will be but will most likely be of a better ride quality. The lower the TPI, the more durable and less flexible the tyre. An MTB tyre will have less TPI than a Road bike tyre.
 
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