Tire treatment for 60 year old NOS tires

[Sawyer911]

I'm getting ready to mount a set of NOS motorcycle tires on my 1954 Harley KH. They are 19 X 3.50 tires.

I've had the tires in a climate controlled loft for about 30 years. No sunlight, motors or large temperature swings. No dry rot showing right now.

I want to soften them up to mount them and to prevent any damage from the tire irons.

The bike is getting retired to use for some shows and parade type events no real road trips. Along with the tires I am putting back on the original seat stored along side of the tires.

Is there any product or home brews that can help me soften up the rubber?

I also add a picture of my back in 1995 or so of me and the bike.

Thank in advance,

Sawyer

[javadog]

I've never had any luck with that. Maybe a museum like Barber wuld share their secrets if you ask them.

If you are successful, I'd recommend limiting their use to rolling the bike around. I would not do parade laps on them.

[masraum]

Originally Posted by javadog

I've never had any luck with that. Maybe a museum like Barber wuld share their secrets if you ask them.

If you are successful, I'd recommend limiting their use to rolling the bike around. I would not do parade laps on them.

I was thinking the same. No riding of any sort, just rolling from trailer to spot to trailer.

But I'm happy to be wrong.

If you want the look of old tires that you can drive on, then maybe there's someone that makes retro tires for bikes as there is for old cars.

[WPOZZZ]

What about Formula V Tire Treatment? SCCA guys used to use it to soften up older tires.

[porsche930dude]

Alot of stuff that is good at softening rubber can destroy it over time like silicone and petroleum products. I have use brake fluid but I dont know if thats good in the long run either. I hear boiling in water with wintergreen oil works good too. Its hard to say. Iv put old tires on bikes aswell that eventually cracked out but I didnt preserve them with anything. Rubber just doesnt like being bent in a way other than how it was molded

[Por_sha911]

I wouldn't trust those tires to be ridden. Even if they don't explode, you will find them degrading almost instantly. Find a second set of retro look tires.

Does Coker Tire (in Chattanooga TN) offer motorcycle tires?

[masraum]

Originally Posted by Por_sha911

I wouldn't trust those tires to be ridden. Even if they don't explode, you will find them degrading almost instantly. Find a second set of retro look tires.

Does Coker Tire (in Chattanooga TN) offer motorcycle tires?

Yes, they do make bike tires, but they don't make that specific make and model of tire.

[JackDidley]

Light seems to be the enemy of tires. My buddy had a 55 Nomad, mostly original with 50,000 miles that has been stored inside but driven ocasionally for 40 years. Reciept for tires was in the glovebox dated 1966. No dryrot or cracking on the old bias ply tires. He drove over 200 miles on weekend. No issues. Unfortunately he has some health issues and sold it this summer.

[Sawyer911]

Thanks for the ideas and suggestions. The bike is being semi RETIRED. Nearing 70 I just worry about kick starting this one. I do ride my 1966 BMW with a sidecar often but it has lower compression and is easier to kick start.

If I run the KH it will be just to weekly cruise ins about 2 1/2 miles from home, AMCA meet about an hour away will be trailered. Not worried of exploding as they are getting brand new tubes, probably more chunking off bits before total disaster.

I was thinking of the idea of chemically treating but as mentioned will these chemicals soften but after evaporating leave the tire drier.

Thought about the tire softeners as well but they seem to be surface treatments and not really meant to be absorbed enough to help.

My other thought is maybe get them warmed up and a good dose of talcum powder to reduce any friction to slide them on.

Thank again,

Sawyer

[javadog]

Maybe get a second set of wheels and try to mount these tires for when it becomes a display piece, for good. Mount a fresh set of whatever tire looks the most vintage on a second set of wheels for occasional rides. That's what I do.

Nobody looks at the tires anyway, they look at the bike. And almost nobody knows enough about it to criticize the tire choice.

Pop a tire in a corner and that tube won't last five feet. I've literally pressed tire removal tools through a sidewall trying to unseat a bead. In a tire that had never been run and was less than 20 years old. Maybe you'll have better luck...

[BK911]

Awesome picture!
Especially the 'stacked.

[911 Rod]

Do they pass the fingernail test?
Or are they so hard you can't push your fingernail into them?
I agree that they should just be rollers.

[herr_oberst]

That's a good looking bike! Hard to believe it's a 54; it looks newer (even in that vintage picture!)

If it was mine, I'd just throw some K70 or K81 Dunlops on it and call it a day. Vintage enough look, and you can still get 'em brand new. (Or, if I was feeling flush I might take a look at the Firestones that Coker sells, to keep that Made in USA vibe but my goodness Coker is proud of their stuff!)

[jhynesrockmtn]

Originally Posted by WPOZZZ

What about Formula V Tire Treatment? SCCA guys used to use it to soften up older tires.

I still have some on the shelf from when I raced, coincidentally, a Formula Vee. I used it to try and extend tire life. Aging rubber and reduced grip were the enemy.

[Zeke]

I've used the brake fluid with no long term damage. I can't say whether it is beneficial or will doing anything to "help" now.

Make sure you use plenty of ArmorAll on the tread.

[ted]

I doubt they will survive the rim mounting process.
New tires on that bike will make it handle like an original.
Nothing built with tires was designed to do it on 60 year old rubber.
Tires don't begin to age until they are mounted so said a tire store guy.
Surprise your wife with Motorcycle tires this year.

[pwd72s]

I'm another who'd vote for using something from Coker Tires..

https://cokertire.com/instantsearchplus/result?q=motorcycle+tires&page=4

[ted]

Originally Posted by pwd72s

I'm another who'd vote for using something from Coker Tires..

https://cokertire.com/instantsearchplus/result?q=motorcycle+tires&page=4

if you are dead set on the 60 year old tires try some

[unclebilly]

From ChatGPT

Mounting 60-year-old NOS motorcycle tires is possible, but treating them to “soften” the rubber is not something modern tire science generally recommends—because the compounds that keep a tire flexible chemically break down over time, and no topical product can truly restore them.
But since you’re using the bike for shows/parades (low speed, low load, low heat), you can take some careful steps to mount them safely and protect them during installation.

Below is the safest, most practical approach.

⸻

✅ Realistic Goals With Old NOS Tires

For 60-year-old tire rubber:
• You cannot chemically restore flexibility to original condition.
• You can temporarily improve workability for mounting.
• You can preserve appearance and prevent cracking during and after installation.

⸻

✅ Before Doing Anything: Inspect Carefully

Even if stored perfectly, look for:
• Micro-cracks when flexing the sidewall
• Hard spots
• Bead cracking
• Casing distortion
• Chalkiness on the surface

Even tiny cracks at the bead area can cause trouble during mounting.

⸻

✅ Safe Ways to Make the Rubber More Workable for Mounting

1. Warm the tires — safest and most effective

Old rubber becomes more pliable when warmed, not when coated with chemicals.

Best method:
• Put the tires in a warm room at 85–100°F (29–38°C) for several hours.
• Or leave them near (not on) a baseboard heater or a space heater from a safe distance.

This softens the casing enough to ease mounting without damaging historic rubber.

⸻

2. Use proper mounting lubrication — crucial

Use a dedicated tire mounting lube, not WD-40, not dish soap.

Best options:
• Ru-Glyde (rubber-safe, water-based, dries without residue)
• Commercial tire paste/lube
• A 50/50 mix of glycerin + water

Lubricate:
• The bead
• The rim edge
• A few inches of the sidewall for slip

This prevents tearing the bead or leaving spoon marks.

⸻

3. Nylon or plastic-tipped irons

Regular steel tire irons will mark old rubber.
Use:
• Nylon rim protectors
• Plastic-tipped irons
• Or wrap your irons with heat-shrink or heavy tape

A small manual bead expander can also help reduce spooning force.

⸻

❌ What NOT to Use

These products either damage old rubber or only make it look “wet”:
• Silicone spray – surface shine only, no softening
• Armor All – can accelerate cracking on vintage rubber
• Brake fluid – old bikers used it, but it destroys tire compounds
• ATF – petroleum-based, causes swelling and bead failure
• Diesel/kerosene – destroys rubber chemistry
• “Tire restore” solvents – mostly snake oil

None of these can restore lost plasticizers.

⸻

✅ Post-Install Preservation

Once mounted:

1. Treat with a protectant that actually works

You want an anti-ozonant, not a shine product.

Best options:
• 303 Aerospace Protectant (UV and ozone protection, non-silicone)
• Griot’s Garage Rubber Prep/Protect

Apply sparingly and reapply a few times a year if the bike sits on display.

⸻

2. Keep tires inflated, but not at max

Store around 75–80% of operating pressure to reduce casing stress.

⸻

3. Keep away from:
• Electric motors (ozone)
• Furnace ducts
• Sunlight
• Welders
• Air compressors and generators

These are ozone sources that accelerate sidewall cracking.

⸻

❗ Important Safety Note

Even with perfect storage, NOS tires over 20 years old are not recommended for highway speeds.
For parades, shows, slow riding, they’re typically fine if the carcass is structurally sound.

If you ever want to ride the bike at highway speeds, swap to new reproduction tires.

⸻

�� If you’d like, I can also help with:
• Tips for mounting vintage clincher or bead-edge tires
• What to look for to assess structural integrity
• Recommendations for reproduction tires that match original tread patterns (if you change your mind)

Just let me know!

[Sawyer911]

Really appreciate the ideas here. The tires are soft enough I can leave a finger nail mark and after a short time it disappears.

Unclebilly thanks for this info, I never used ChatGPT yet. But alot of this info makes sense. Seems like a good direction to start.

The bike will be limited in use. I do have a set of 18" rims that I had run for several years and now are in need of tires and seeing I have not run the bike for sometime I am re-installing the original rims and seat that were on the bike when I first got it in the mid 90s. I tore down the bike for a repaint, rewire and re-tire. It needed a refresh as the (poorly prepped) non original paint and old cloth wires were deteriorated pretty bad.

It is Harley Davidsons 50th Anniversary edition parts for Ks are not too common and I've had my fun on it. I've had it about 30 years and now it will retire to just show. I do run my 66 BMW R60/2 regularly and with the sideways kick starter, magneto, and lower compression is easier on me.

I am casually looking for a 100th Anniversary 2003 Harley Softtail Springer as an additional stable mate. Electric start and the look I like.

Sawyer