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Request tire/tyre advice.
#812615 06/15/20 5:30 am
Joined: Feb 2018
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I'm to the point on my '69 Thunderbolt project where a decision must be made about tires.

I was leaning toward a more modern design, Avon AM26, Michelin, Continental, all have what I call wannabe race tires. The ContiAttack radial gets really high reviews. But I started thinking more about how I plan to ride this bike. And I do plan to ride it, I'm building it to ride not hide. But I plan to explore the back roads of East Oklahoma which can switch from asphalt to dirt to gravel and back to asphalt. Now it may be old fart bias, I may be totally wrong, but the impression I have is that these race like tires may be great on pavement but what about gravel?

I'm leaning heavily toward the IRC GS-11

I'm not interested in scraping the rubber from the pegs. I'm not interested in period correct look. I want a good safe tire for a wide variety of road surfaces.

Thanks in advance for your advice/recommendations.

Tracey

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Re: Request tire/tyre advice.
Tracey Spear #812634 06/15/20 11:37 am
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K-70

Re: Request tire/tyre advice.
Tracey Spear #812638 06/15/20 11:53 am
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K-70

its an antique but what youre descibing is where it shines

the only place, really


every day you do not take a chance is a day of your life that you will never get back.
Re: Request tire/tyre advice.
Tracey Spear #812654 06/15/20 3:24 pm
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K70 again, they seem to handle quite well for gravel roads and well on road, the only other alternative is Pirelli Trials tyres which are fine on road upto a speed.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Re: Request tire/tyre advice.
Tracey Spear #812684 06/15/20 7:06 pm
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I would not put those IRC tyres anywhere near a bike of mine. They don't even publish the speed rating and load index


BSA B31 500 "Stargazer"
Greeves 200 "Blue Meanie"
Greeves 350
Greeves 360
Suzuki GSX1100 EFE "Sorcerers Apprentice"
GM500 sprint/LSR bike "Deofol"
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Re: Request tire/tyre advice.
Andy Higham #812691 06/15/20 7:49 pm
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Hmm Interesting point. They get good reviews on the tire sites.

Re: Request tire/tyre advice.
Tracey Spear #812695 06/15/20 8:26 pm
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Ya know. I started out biased against K70's just cause they represent '60's tire technology. I thought if there is any one area tires have advanced a lot, tires ought to be it. But the more I research, and think about it, most of the boasted advantages of the race tire lookalikes seem to be based on on a dry pavement knee dragging riding style. Something that at my age I'm just not into any more. The two lanes I want to explore can easily go to dirt, gravel, sand on asphalt, ect. K70's are starting to look better and better.

Re: Request tire/tyre advice.
Tracey Spear #812717 06/15/20 10:32 pm
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got k70s on my 68 A65 and 72 T120 they look 'right' and for my backroads riding are perfectly suited rear lasts 3k miles front longer but tend to 'cup' I aint a robot


1972 Triumph T120
1968 BSA A65
1968 MGB Roadster
1979 Chevrolet Camaro Berlinetta
1969 Honda Mini Trail
1939 farmall f30 tractor
2004 Honda Shadow Aero
1972 BSA Thunderbolt
1975 yamaha xs650b
1972 Norton commando
2 olive drab WWII military bicycle replicas
Re: Request tire/tyre advice.
Tracey Spear #812718 06/15/20 10:33 pm
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i do not know whether the modern K70s are built the same inside as the old ones or whether only the appearance is grandfathered. they may be improved.

you can buy some of the classic tirez in trackday compounds, so iknow they do it.

a good place to check would be recommended inflation pressure on the sidewall. newer designs take higher prezsures


every day you do not take a chance is a day of your life that you will never get back.
Re: Request tire/tyre advice.
Tracey Spear #812727 06/15/20 11:01 pm
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Another driver for my bias is the awful wheel locks that I removed from the 60's era K70 and the weight it took to offset.

Surely modern K70's have improved and I can properly dispose of this ridiculous weight.

[Linked Image from i.postimg.cc]

1 member likes this: ChiefRider
Re: Request tire/tyre advice.
raf940 #812731 06/15/20 11:13 pm
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Originally Posted by raf940
got k70s on my 68 A65 and 72 T120 they look 'right' and for my backroads riding are perfectly suited rear lasts 3k miles front longer but tend to 'cup' I aint a robot


Your not daring enough, I got 4000 out of my K70 rear, although it went from being unsafe, skipped past dangerous and straight to scary by that point, anything over 70 and it was just weaving at the back end.


I’ve also found the K82 (tt100 look alike tread) to be pretty reasonable off road, they seem to have more of a block tread pattern as opposed to the road riders which are more cut into the tyre effect than added to the outside if you get my meaning.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Re: Request tire/tyre advice.
Tracey Spear #813161 06/19/20 4:20 pm
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No Allan, I'm not near as daring as I once was. My exhaust scraping days are over. I'm more into fun, safe, moderate cruising on two lane back roads and enjoying this old bike.

My thanks to all who offered advice and opinion.
.
After discussing tire options with Eric Colvin of Colvin Motorcycles in OKC I settled on the K70's. Eric's works on about anything, but he's an old flat tracker and has a soft spot for vintage motorcycles. He agreed that the more rounded modern tires don't perform well on dirt or pea gravel surfaces. He puts in a couple hundred miles or more a week road testing customers equipment. So he is exposed to a lot of bikes and tires. He's a big fan if Dunlop K181's but thought that might be a bit aggressive for me. Ultimately I agreed and settled on K70's. They look right, fit right, and perform reasonably well.

The knee draggers may make it to the watering hole first, but hell these days I drink more Boost than Beer.

Y'all ride safe. I expect to be out there sometime this summer.

1 member likes this: Gary E
Re: Request tire/tyre advice.
Tracey Spear #813189 06/19/20 7:03 pm
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some good roads in oklahoma. where you in the east is two-lane heaven for winding stuff, but if you go into the middle and farther west into the section lines you can make serious speed in the country.

way west is best for that


every day you do not take a chance is a day of your life that you will never get back.
Re: Request tire/tyre advice.
Tracey Spear #813216 06/19/20 10:08 pm
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Heidenau K34 rear 3.50-18 K44 front 3.25-19.

How many people are racing K70s today?

Last edited by Semper Gumby; 06/19/20 10:14 pm.
Re: Request tire/tyre advice.
Semper Gumby #813240 06/20/20 4:30 am
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Originally Posted by Semper Gumby
How many people are racing K70s today?
I don't know, maybe in classes where only stock tires are allowed? laughing


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: Request tire/tyre advice.
DavidP #813328 06/20/20 10:49 pm
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Poke fun all you want. Eric mentioned he sells a lot of K70 to those who race vintage classes. And yes, rules dictate pretty much stock tires!.

Racing on K70? What kind of argument is that. So what if they aren't designed for the track? Do normal cars drive on NASCAR tires?

Re: Request tire/tyre advice.
Tracey Spear #813363 06/21/20 2:20 am
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Rubber must have improved , 2020 k70s are not 1970s, hurray.!
I still wont use them. As soon as the tt100 came out they were old stuff.
K70s and wide handlebars are a good combo.

Last edited by gavin eisler; 06/21/20 3:13 am.

71 Devimead, John Hill, John Holmes A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: Request tire/tyre advice.
Tracey Spear #813390 06/21/20 10:58 am
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One of the worst things about K70s is the low mileage out of the rear tyre compared to the price of them. The road riders look good on these bikes and handle well. They also don’t suffer with white line issues like the TT100’s

I doubt anyone would race with them but bike geometry makes a big difference as I found with my canam

Last edited by Allan G; 06/21/20 10:58 am.

Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Re: Request tire/tyre advice.
Tracey Spear #813724 06/23/20 9:31 pm
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K 70s will probably work fine for you for your intended multi surface riding. They were a “go to” tire for that sort of thing until the K81s came out, as someone said above. It’s been many decades since I used K70s but my recollection is that when used on the street they wore flat in the center with square shoulders fairly quickly, which gives a less than optimum transition into corners. Race them? I think we didn’t have so many choices back then and these tires worked OK for a lot of surfaces and uses. I rode my first road race on K70s more than 50 years ago on an X-6 Suzuki in the 250 production class (never noticing any lack of traction) and I rode scrambles on my 650 Triumph with them too. But truth told, when K-81s became widely available I never used them again on asphalt. I’m a big fan of Avon AM26s nowadays for these old bikes.


Moderated by  Allan G, Jon W. Whitley 

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