Inner tube size vs tire size

[EVENKEEL]

When you buy a new tube is the size the same as tire or is it smaller and if so is the height or width of tube smaller? My back tire is 130/70 18

The dealer sold me a tube that is 3.25/3.5  18RP does this sound right?

 

[Kwasaki]

Does it fit. ????

[Crossy]

It's been a goodly while since I've done bike tyres but I would say a 3.50/4.00 would be a better fit but the 3.25/3.50 will be just fine.

 

Rubber is pretty stretchy stuff ????

 

[EVENKEEL]

15 minutes ago, Kwasaki said:

Does it fit. ????

I don't have a flat yet. I bought in case. I had a flat on front and getting the right size was hard. Went to dealer and they are ****useless. 

 

Am wondering should the sizes be exact or should tube be a bit smaller and if it should be smaller. Should it be smaller in height or width.

[Crossy]

2 minutes ago, EVENKEEL said:

Am wondering should the sizes be exact or should tube be a bit smaller and if it should be smaller. Should it be smaller in height or width.

 

If you have a look at the range of sizes each tube fits here https://www.wheelhousetyres.co.uk/tubes/road.html?LIGHTSPEED_PRODUCT_SIZE=32 it's pretty large.

 

Ideally the tube should be the same as the tyre, but a size bigger than the tube max isn't going to hurt.

[Kwasaki]

2 hours ago, EVENKEEL said:

I don't have a flat yet. I bought in case. I had a flat on front and getting the right size was hard. Went to dealer and they are ****useless. 

 

Am wondering should the sizes be exact or should tube be a bit smaller and if it should be smaller. Should it be smaller in height or width.

Yeah you doing a good thing if it's difficult where you are to find a competent puncture repair guy.

What you have will be ok.

You can get inner tubes that are not round just straight in length and you can put them in without wheel off but they still need a pump. ????

[jackdd]

Which brand did you buy? Usually the packaging states in which tires the tube fits.

So this 4.00 - 5.10 tube fits in a 120/80-18 tire, which is quite similar to your 130/70-18 tire.

The inner tube which you bought is too small. It will probably somehow work, so as a backup it might be sufficient, but for long term use you should get a bigger size.

 

[Neilly]

On 9/19/2020 at 1:19 PM, EVENKEEL said:

Am wondering should the sizes be exact or should tube be a bit smaller and if it should be smaller. Should it be smaller in height or width.

Normally when you buy a tube it covers a range of sizes, it'll do smaller or larger than itself (obviously)...but ideally 'your' size should be written on the package or tube itself.

 

I'd say the one you got was on the small size according to this table...

 

 

[Damrongsak]

"Inner tube size vs tire size..."

My wife and I haven't had a problem with that all these years.