Stretching Clincher tires

[George Hand]

It is summertime & the weather is hot, time for me to stretch some older 30 x 3 1/2 tires to mount for a roller chassis. I am looking for the mounted size car tire to use to stretch the old tire I had seen it in years back on the Forum but have not found it today. I believe it was like 165/75/14 or maybe 175/75/14?

[DanTreace]

Here is that post:




By Allan Bennett on Wednesday, May 05, 2010 - 11:37 am:
Old hard tyres have often shrunk. Borrow you wife's dressmaking tape and measure the inside circumference and compare this to the circumference of your rim and you will see what you are up against. Peter Kable is right when he says they need to be stretched first. I stretch them by levering them over an uninflated 165 x 14" tyre and then inflating the tyre. Sometimes it takes two steps, using a slightly higher profile tyre for the second stretch. You might have to leave them for a week or two to achieve enough stretch. Sometimes they will break the bead if they are too hard.

When I fit them I use tyre shop lubricant. It is a lot less messy than soapy water and does not dry out. I put a rim liner cut from an old 13" inner tube directly onto the rim, and fit a lightly inflated tube into the tyre. I fit both sides together, to avoid pinching the tube trying to lever each bead on separately. I use a portable third hand in the form of a clamp to hold both sides of the tyre in the rim at the valve. That leaves both hands free to work the tyre levers, working both ways around from the valve. At the end, one bead will go on first, leaving about 6-8" of the second bead to lever on at the end. All of this is done at waist height on benchtop.

A key to fitting any hard-to-fit BE tyre is tyre lever itself. Mine are 18" long, have the usual shallow curve at one end like the genuine T levers, and at the other end is a sharply cupped hook which is about the same profile as the edge of the rim. It is easy to get under the tyre bead and closely follows the rim edge as you lever, so keeping well away from the tube. Mine are German Dowidat brand and the hook end is about half as thick as the cheap oriental imports.

[George Hand]

Dan, Thanks for the info, now the hunt for a mounted 165/75/14, getting hard to find. Pick n Pulls salvage yards already have the wheels & tires removed when the cars are placed in a yard. I do not need to measure anything I already know they have shrunk, I was able to get one apart this afternoon after setting in the sun. My Weaver Model E tire machine helps & my tire iron collection I have had for quite awhile. Thanks again. George

[Allan]

George, with the multiplicity of tyre sizes and profiles these days, there are likely to be other combinations which will work. Take your 30 x 3.5 tyre with you and try it on against whatever you can find. The higher the tyre profile the better, as this will expand more when you inflate it, so you get more stretch.

Allan from down under.

[desertexplorer]

Thought I’d reply to this older post and add a link from a tire site that calculates different tire sizes. The site’s great for finding the right size tire to stretch those old shrunken tires of different sizes whether a 30 x 3 1/2 (23”) or 32 x 3 1/2 (25”), etc. The site is mainly for comparing tire sizes, RPM and speedometer ratios but works great to show outer tire diameter.

https://www.tacomaworld.com/tirecalc

I’ve used this method to stretch old shrunken tires in the past and does work but needs to go real slow over a course of a few weeks and be out in the hot sun as mentioned to soften them up.

[Erik Johnson]

Photo courtesty of Dan Hatch.

My father used this same procedure 60 years ago to stretch a set of metric Dunlop 875 x 105 clincher tires so they would fit the 27 inch wheels of his 1910 IHC. He said he let each tire sit on the modern tire over night.

Note that this works only with clinchers because there is no wire in the bead. It will not work with straight-side tires due to the wire in the bead.

[Allan]

It took me four weeks to stretch a set of 5 new old stock Olympic BE tyres. They had been well stored in the dark, but had shrunk almost 2" in circumference over some 50 years.My friendly tyre fitter set me up with four different rim/tyre combinations of differing diameters. I started with the smallest one and progressed up the series every second day. At the end I used a new trick. The tyres were fitted over a 23" Chev split rim, and the rim tool jacked apart a firther 1' at the split. That really made the job easy. All of this was done in summer! Heat and proper tyre lube are your best friends.

Allan from down under.