New tire weirdness

Have just purchased a new Dunlop (rear) tire. Purchased from a large online seller who also (like so many others) now sells on Ebay. Purchased as a 4.10 H 19 K81 tire. Although nowhere on the tire does it say K81 in the stamped/raised letters, it does say roadmaster TT100. Although it is not marked K81, it does have the identical tread pattern of the K81 that I removed from the wheel. The tire is marked as being made in Indonesia. Is this tire now considered the replacement for, or the same as the K81? Don't really care one way or another as I am going to go ahead and use it. I know some of these old tread pattern replica tires are considered universal, meaning they can be used front or rear. But the weird thing, as I mentioned in the thread title is, the rotation arrows indicates one direction rotation if installed on the rear, but the arrow on the other side indicates it should be installed in the opposite rotation direction if installed on the front. Can anyone weigh in here and shed some light on, what to me, are unusual directional indicators?

The original Dunlop K81 also went on one way for the front and the other way for the rear fitment.
Did the vendor sell this as a Dunlop tire or Dunlop “type” tire?

Was sold as a Dunlop tire and does have the Dunlop brand marking in molded raised lettering on the sidewall.

Tires. of course, are not solid, they are soft and compliant with the road and the vehicle's forces.

The direction arrows are there to ensure that the wheel's pulling loads on the tire's internal cords ("threads"} are pulled in tension, and not pushed in compression. That way a tire on the rear wheel pulls on the cords during acceleration while a front tire's wheel during heavy braking also pulls on the tire's internal cords.

The K81 is the TT100 tyre they also make one in a softer compound for track work.

quawk said:

The tire is marked as being made in Indonesia.

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Yes, TT100s haven't been made in England for more than thirty years. Production moved to France then Japan and now Indonesia although apparently a few are still made in France.

quawk said:

Have just purchased a new Dunlop (rear) tire. Purchased from a large online seller who also (like so many others) now sells on Ebay. Purchased as a 4.10 H 19 K81 tire. Although nowhere on the tire does it say K81 in the stamped/raised letters, it does say roadmaster TT100. Although it is not marked K81, it does have the identical tread pattern of the K81 that I removed from the wheel. The tire is marked as being made in Indonesia. Is this tire now considered the replacement for, or the same as the K81? Don't really care one way or another as I am going to go ahead and use it. I know some of these old tread pattern replica tires are considered universal, meaning they can be used front or rear. But the weird thing, as I mentioned in the thread title is, the rotation arrows indicates one direction rotation if installed on the rear, but the arrow on the other side indicates it should be installed in the opposite rotation direction if installed on the front. Can anyone weigh in here and shed some light on, what to me, are unusual directional indicators?

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All universal tyres are marked this way as far I'm aware

The forces are opposite on the front and rear due to the rear pushing the bike along, and the front being pushed along. The tyres are built (layered) in a certain direction in order to handling this.

Fast Eddie said:

The forces are opposite on the front and rear due to the rear pushing the bike along, and the front being pushed along. The tyres are built (layered) in a certain direction in order to handling this.

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Yep that's the theory
This is why I never use the back brake or use engine braking

ILLF8ED said:

The original Dunlop K81 also went on one way for the front and the other way for the rear fitment.
Did the vendor sell this as a Dunlop tire or Dunlop “type” tire?

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Many tire tread pattern share that trait.

The K81 is the TT100 tyre they also make one in a softer compound for track work

The race compound tyre is a 100/90x19 TT100GP, a 410x19 is normal street compound.

The explanation , at the time , was the canvas ' cords ' were a belt , overlapped ends . Would push together rotated right , whereas the ' end ' outermost was pulled away from the other , if it was into the primary force .
Were U K & IRISH tt 100 , and ' nylon ' made in japan , which were more plastic . So youd fall off easier . Particularly in the wet .

A ' R ' Compound ( 4.25 - 18 K 81 R ) had a more durable carcass . ( discernably so - twice as stiff ) and was the era of the Perrili Phantom , which was soft outer , harder compound center tread . So id wear less .

Dunlop ' Tri Gonic ' the fight with Ago , was INTO the Corner . Like wot a speedway bloke does .

baz said:

Yep that's the theory
This is why I never use the back brake or use engine braking

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You don't use engine braking? Are you sure you ride a Norton?

Matt Spencer said:

Dunlop ' Tri Gonic ' the fight with Ago , was INTO the Corner . Like wot a speedway bloke does .

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No...he was using triangular KR76/KR73 race tyres, not trigonic K81/TT100s road tyres.

possm said:

The K81 is the TT100 tyre they also make one in a softer compound for track work

The race compound tyre is a 100/90x19 TT100GP, a 410x19 is normal street compound.

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Are race compound TT100GP tyres still available in the UK or anywhere in 18 inch ? I do not know what I would do, if I could get decent tyres.

SteveA said:

You don't use engine braking? Are you sure you ride a Norton?

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Well it was meant as joke hence the winking emojis but hey ho

Thems all trigonics , Moit .


NdI thoughtitwas a KR 84 rear ? Thats a 76 Front . a 327 compound I think was thestickyone . Funny story theier . No , IT HARD . Some people think your try'n to pull one .

The PROBLEM withem is the teeter totter . Your stable CRANKED OVER . Front ( and rear ) the CENTRAL DRAINAGE GROOVE is why they tramline , follow road ridges , and camber to a degree .
Twith Twith . Less relephant full tit . But did I tell you about the Track Join in the club track Pukekohe . Anyone at the foist C R M R C do should remember , Dont get yourself aft of the rear axle.
The ballance aint then good .
By the Way .
PUSH on the BARS in a Speed Wobble / Weave . It DAMPS IT . Pull Back - Its liable to throw ya round and amplifyit . Like a Z1 or other kwickersaki .

Ive never cottoned to the K 70 F , K81 R on the oily trpls . Seen one that accomplished my theory . Hit a car at 80 . The K 81 brakes GOOD , Layed Over . Astonishingly so , on occassion .

While the front'd wash out , full brake , layed over , on a K 70 . Unless you use the berm .

They were K - 81 , untill ;


Front was still KR 76 , but they wereabit quickerthanthat . SEE the SHORT SIDEWALL . Tough as Old Boots . the CASING .

The Amorican K 81 R from around 80 , was A LOT stiffer in the casing / carcasss . So they wouldnt blow in death valley .
On your Goldwing , bagger , loaded , and throw the wife . Legedly they were developed for THAT . But had other uses .

That theres NOW a T T 1 0 0 .

Crikey .


OOPS.


SORRY ABOUT THAT .

Ah Well , one gets started , you know .
TRIGONICs , All Round ! .

trigonometer​

(ˌtrɪɡəˈnɒmɪtə )
noun
any of various instruments used in trigonometry

Old mutter Cycle Mag had Dunlop itterating on suchlike , atta da tyme .

An odd bike foran odd tyre , Mon .

ARRGGHH .


Peter Williams & Tom Arter . You thinkitwas a 750 at foist . P W's pater was A J S race Shop chief , so ' young paeter ' was a chip off the olde block / bloke . Tencnicalically .

The new soft compound TT100s tramline like crazy, but they're great when loaded up in a corner.
I just wish they lasted longer