Dunlop K70 tyres - I'm confused

[Grewth]

AFAIK, Yamaha fitted Japanese Dunlop K70 tyres to the XS1, XS1B, and XS2.
3.25x19 up front, 4.00×18 at the rear.
I've looked up the K70 range on Dunlop's website, and the rear size is 400S18, meaning a 112mph speed rating.
Front tyre is 325P19, the P speed rating is just 93mph - not adequate for the XS.
I was always taught that you should never fit tyres with a lower speed rating than the bike will do, so I'm assuming the the original 1970's K70's had a higher rating.
Did Dunlop redesign their tyres with a weaker construction, or have they just been downgraded for safety reasons ?

 

[Mailman]

The factory original rubber on my XS2 was a K70 on the rear and a ribbed tire on the front ( unsure what that pattern is called ) when I restored it, I put K70’s front and back. The bike always handled well and never presented a problem , but I don’t think I ever pushed it over 80 mph. ( or 128 kph ) and then not for very long.
More because I wanted my motor to last.

 

[cra-z1]

I would assume there is a safety factor built into the tire. They will not blow up if you hit 93 MPH. If you can sustain anything near that speed on the 650 more power to you. With the advance in tire construction I would guess the tires made in the 70's are nowhere near as safe as they are today.

 

[WideAWAKE]

The factory original rubber on my XS2 was a K70 on the rear and a ribbed tire on the front ( unsure what that pattern is called ) when I restored it, I put K70’s front and back. The bike always handled well and never presented a problem , but I don’t think I ever pushed it over 80 mph. ( or 128 kph ) and then not for very long.
More because I wanted my motor to last.

View attachment 217979

Believe their ribbed front tire was the f83 - no longer on the market.

 

[Wingedwheel]

(I was always taught that you should never fit tyres with a lower speed rating than the bike will do)

I think it’s more about the speed rating the rider will do.

 

[gggGary]

Been riding a lot of front 3.25 K70's new, a few old, a lot of miles no issues.
Just got one from Rocky Mountain motorsports yesterday.

 

[Jan_P]

AFAIK, Yamaha fitted Japanese Dunlop K70 tyres to the XS1, XS1B, and XS2.
3.25x19 up front, 4.00×18 at the rear.
I've looked up the K70 range on Dunlop's website, and the rear size is 400S18, meaning a 112mph speed rating.
Front tyre is 325P19, the P speed rating is just 93mph - not adequate for the XS.
I was always taught that you should never fit tyres with a lower speed rating than the bike will do, so I'm assuming the the original 1970's K70's had a higher rating.
Did Dunlop redesign their tyres with a weaker construction, or have they just been downgraded for safety reasons ?

Well spotted ... I think you in the UK had an inspection of the bikes roadworthiness and safety before they even was allowed to sell them.
I dont think anyone would try it in Sweden Back n those days Should a No Nonsense government inspector suspect he was taken for the " Proverbial Ride " on subpar tires from the factory .. That would be something to regret. One could expect next level inspections for many years to come
Those inspectors are generally experts studying the paper work aka bike specs and tyre spec and then the hammer falls.
And I don't believe the factory would make such a blunder either " Loose Face "

I should guess it was different ratings and harder less safe tires . from the start ..
On a side note I used Dunlops quite many years dont remember what type.
They did not last long. So I quit using the brand.

 

[GLJ]

I bought a set of Duro tires for my survivor XS2. 325x19 front and 400x18 rear. The front is rib style which is correct for the bike, rear also looks correct. $141USD for the pair. Speed rating is less than what the bike will do but more than what it will see with me on it. I only have 400 smiles on them but so far I can find no fault with them. On my other XS2 I just ordered a set of Conti Twins. I wanted a better tire as I take trips on it and it sees higher speeds for longer periods of time with the added weight of saddle bags. Pick tires based on how the bike will be used. I'm not as a aggressive a rider as some others here so a cheaper tire works for me.

 

[GLJ]

They will not blow up if you hit 93 MPH.

As he said just because you exceed the speed rating doesn't mean they will instantly disintegrate. That rating is based on speed+weight on tire+time.

 

[1978 Tracker]

I found vintage Dunlop K70"s on Amazon. Ordered a set for my Tracker.

 

[WideAWAKE]

I just got some IRC gs11 for my CB.

A pretty close pattern to what would have been factory original.

A bit of a blocked rib for the front.

They feel good but havnt gotten them on the road yet.

 

[GLJ]

I just got some IRC gs11 for my CB.

A pretty close pattern to what would have been factory original.

A bit of a blocked rib for the front.

They feel good but havnt gotten them on the road yet.

View attachment 217996

I looked at them but decided on Continentals. Let us know how you like them.

 

[gggGary]

Just looked now and I see bill put the 3.50 on weathervane. Rides, fits fine, was looking at it I as was browsing and thought jeeze that looks fatter, yup.
fills the space under the fender a bit better.

 

[Grewth]

Just looked now and I see bill put the 3.50 on weathervane. Rides, fits fine, was looking at it I as was browsing and thought jeeze that looks fatter, yup.
fills the space under the fender a bit better.
View attachment 218002

That's exactly the sort of look I'm after.
I simply don't like seeing modern, low aspect tyres on old vehicles, destroying the "original" appearance completely.