Topic: sohc 750 k4 which size tyre are the best

[neil10]

trying to decide best size tyres front and back

[kghost]

Stock     

100/90-19

110/90-18

[HondaMan]

Kghost has it right, especially for all-around riding.
If you live in the mountains, and don't tour with heavy loads, you might like these:

TT100 K81 series: front 4.10x19, rear 4.50x18. Buy the British version, like the Brit Dunlops, for best results. The Japanese Dunlops look similar, but don't hold as well in the wet or on sand.

These are "V" profile, trigonometrics. Good for cafe' racers.

For all-around riding, like commuting and other slaloms, the ones he mentions are my first choice, too. 

[kghost]

Big Dunlop fan here 501 GT's

[HondaMan]

Big Dunlop fan here 501 GT's

What are the features of those tires, "K"? I'm looking for new shoes for Baby...

[kghost]

Well they have excellent balance and uniformity.

I just put a new one on the back of the black bike while at the same time my buddy put a set on his K4.

His required no weights, mine required no weight shift.

As far as ride and handling, I prefer them to anything else.

I think they stick better than the Bridgestones.

In addition to great traction they release traction in a controlled predictable manner.

They sure don't release all at once. Under extreme use I can feel the back start to go way before its gone.

Now I have an oversize on my rear...120/90-18. Given the pinching the life has not been super high.

I got 7000 miles before I swapped it. Probably would have gone anothe 500 miles no sweat...but the timing was right.

Other people running them  have gotten more life. Its sure not a touring tire as far as milage.

Sticks, wears even, and doesn't screw up the handling.

They work for me

[HondaMan]

Well they have excellent balance and uniformity.

I just put a new one on the back of the black bike while at the same time my buddy put a set on his K4.

His required no weights, mine required no weight shift.

As far as ride and handling, I prefer them to anything else.

I think they stick better than the Bridgestones.

In addition to great traction they release traction in a controlled predictable manner.

They sure don't release all at once. Under extreme use I can feel the back start to go way before its gone.

Now I have an oversize on my rear...120/90-18. Given the pinching the life has not been super high.

I got 7000 miles before I swapped it. Probably would have gone anothe 500 miles no sweat...but the timing was right.

Other people running them  have gotten more life. Its sure not a touring tire as far as milage.

That's always the rub, isn't it? You find one that sticks, it doesn't always wear so well. I think this time, I'll have to go for more mileage, since the price of gas is making me use it for commuting daily. I'm thinking of the 100/90 and 110/90 combo, then I could go up to 18T front sprocket again. Torn between the TT100 profile or not, though... 

[neil10]

Hi can only get the bt45 bridgestones rear in 120x90x18 for rear

[neil10]

if I had v rated at front and h rating at rear How's that sound

[HondaMan]

Hi can only get the bt45 bridgestones rear in 120x90x18 for rear

If I end up with 120 rear, I'll have to stick with the 17T front sprocket. I've grown fond of that quick-response feeling of the 17T and the existing 4.00 rear... 

[kghost]

Well they make the dunlop in 110.

I dunno that with the correct size you wouldn't get more life.

i sure wouldn't judge life from the way I ride.

Dennis kirk I believe had the dunlops in stock as did tucker rocky

[TwoTired]

if I had v rated at front and h rating at rear How's that sound

If you are putting tubes inside tubeless tires, those speed ratings are reduced by one letter.

So, your V rated tire is then rated at 130 mph and your H rated tire is only rated 115 mph.

[coyotecowboy]

OK, Dennis Kirk has TT100's front and rear 4.10/100H-19 front and 4.25/85H-18 rear, and American Moto Tire has them in the same size also.  Are these the Brit Dunlops or the Jap Dunlops?  And how do I tell the difference?   What kind of milage can I expect out of TT100's verus something like a BT45 Bridgestone?

I'm in southern Ks, so I'm quite a ways from the mountains and I have to pound down quite a few flat boring miles before I can get to somewhere fun to ride.  Maybe TT100's aren't the right tire for my riding habits

[Tower]

"Only" 115 mph
Considering the high performance "standard" rating was "S"  (112 mph) for most tyres in 1969, I'd say "H" was darn good.

Tyre speed ratings relate to how well the tyre keeps its integrity (shape mostly) over a period of time at a given speed.  Most tyres can easily go over their rated speed, just not for extended periods of time.  These speed settings are established under controlled conditions, with application matched ideally for that tyre (i.e. best rim design and exact load). 

Ply separation is much less unlikely to be the cause of tyre failure due to speed, and much more likely due to overload, underinflation, wrong size and bead separation.  Ply bonds are put under stress by flexing.  (such as from high speed elongation, but mostly from the factors I already mentioned), and ply separation happens when heat builds up to the point of weakening those bonds. 

As speed increases, the shape of the tyre changes, growing taller and thinner.  Tubes don't substantially alter this aspect, perhaps even shoring up a tyres resistance to changing shape, as long as the tyre and tube have been balanced together.  Ply material and construction, sidewall and bead design, and compound are the major determinants of how well a tyre keeps its shape.

However, the rim is a limiting factor in speed rating and perhaps this is where the misconception that tubes reduce speed setting comes from.

Rims that require tubes, place additional rigidity requirements on a tyre in order for that tyre to be rated at higher speeds.  In other words, a tyre that is able to keep its integrity on a tubeless rim, will break seal much earlier on a tubed rim - not because of the tube, but rather because of the rim and associated effects on a tyre's sidewall behaviour.  Indeed, a tube helps the tyre retains its integrity, past the point where it would otherwise fail without a tube.

Since most tubeless tyres are tested on special tubeless rims, its a safe bet to say they are less capable when used on tubed rims.

If you want to keep those speed ratings accurate, you may of course change to tubeless rims.  Or...use the Honda recommended tyre size, i.e match tyre width to rim and increase height/width aspect ratio, increase tyre pressure, reduce load, and get a really good tyre, tube and wheel balance.

[neil10]

thks

[TwoTired]

"Only" 115 mph
Considering the high performance "standard" rating was "S"  (112 mph) for most tyres in 1969, I'd say "H" was darn good.

Glad you got the joke. 

Ply separation is much less unlikely to be the cause of tyre failure due to speed, and much more likely due to overload, underinflation, wrong size and bead separation.  Ply bonds are put under stress by flexing.  (such as from high speed elongation, but mostly from the factors I already mentioned), and ply separation happens when heat builds up to the point of weakening those bonds. 

The point is, adding a tube, in effect, adds another ply that isn't bonded at all.  This leads to increased heat build up at higher speeds.

However, the rim is a limiting factor in speed rating and perhaps this is where the misconception that tubes reduce speed setting comes from.

Rims that require tubes, place additional rigidity requirements on a tyre in order for that tyre to be rated at higher speeds.  In other words, a tyre that is able to keep its integrity on a tubeless rim, will break seal much earlier on a tubed rim - not because of the tube, but rather because of the rim and associated effects on a tyre's sidewall behaviour.  Indeed, a tube helps the tyre retains its integrity, past the point where it would otherwise fail without a tube.

Since most tubeless tyres are tested on special tubeless rims, its a safe bet to say they are less capable when used on tubed rims.

Well, that's a nice write up...except.
When hand mounting tires I always found the old tube type tire had far less tire bead rigidity than tubeless tires.  There was far more steel in the bead area with tubeless tires.   This, presumably, was to keep a strong air seal between the tire and rim while under lateral loads, which wasn't needed as strongly for tube type tire's.   I have, in fact, cut both tire types seating bead with hacksaws.  The tubless type was far more difficult to cut though and the cross section exposed far more steel on the tubeless tire bead.  Granted the dissection was on car tires not MC tires.  But, simply trying to flex both types of MC tires beads sure seemed indicate a similar construction.  This seems to contradict some of your write up.

Cheers,

[Tower]

@TwoTired, your findings match my own with respect to bead strength and sidewall construction when comparing the older tube to the newer tubeless construction.  Tubeless tyres indeed have stronger sidewall and bead construction as one would expect.  But that's not exactly what I was trying to say.  I was underscoring that its the rim and not the tube per se that determines tyre rating.

What I meant was, tubeless tyres designed for a new rim, but placed on an old rim, would have to have even more rigidity in order to prevent bead separation (for a given speed rating).  i.e. a tubeless tyre on an old rim would separate earlier than a tubless tyre on a new rim, because of the rim design, not because of the absence or presence of a tube.  In other words, rim design places additional rigidity requirements onto a tubeless tyre, that it does not place onto a tubed tyre, because old rim design relies on the tube for tyre integrity and not on sidewall bead strength. 

As for the heat aspect:
Agreed that an inner tube acts like an additional ply.  However, the question is how does that extra ply respond to the forces acting on the tyre at speed.  Recall that bias plys actually add rigidity as tyres expand with speed, whereas radial plys increase sidewall flex. A key differentiate on motorcycle tyres is that under speed, radial plys detract from strength.  So how does an inner tube act?  As speed increases, an inner tube inflates more, i.e. increases rigidity, and acts like a bias ply. 

What of friction?  We know that friction between plys is a factor.  So, does friction between tube and tyre play a role?  Friction between chord or steel plys is to a large extend due to the material itself.  If it gets hot enough, chords separate and lose adhesion effectively shredding the rubber,  This is less of a factor with tubes, as tyre movement against tubes involves much less friction - tubes aren't "glued" in place.  Inner tubes don't shred tyres or vise-versa.  However, some of the excess tube heat would transfer to the rim and some would increase the temperature of the chord plys, and in that manner potentially effect tyre integrity. So, yes, an inner tube adds heat, but much less heat than is generated by the chord plys themselves.  Its only my guess, but I should think that the small incremental tube heat would not effect speed rating to any great extent.

[HondaMan]

OK, Dennis Kirk has TT100's front and rear 4.10/100H-19 front and 4.25/85H-18 rear, and American Moto Tire has them in the same size also.  Are these the Brit Dunlops or the Jap Dunlops?  And how do I tell the difference?   What kind of milage can I expect out of TT100's verus something like a BT45 Bridgestone?

I'm in southern Ks, so I'm quite a ways from the mountains and I have to pound down quite a few flat boring miles before I can get to somewhere fun to ride.  Maybe TT100's aren't the right tire for my riding habits

I think the only way to find out: have the dealer read the side of the tire. It says, "Made in..." somewhere, by law.

Although, you may be right about the long, straight rides. 

[coyotecowboy]

OK, Dennis Kirk has TT100's front and rear 4.10/100H-19 front and 4.25/85H-18 rear, and American Moto Tire has them in the same size also.  Are these the Brit Dunlops or the Jap Dunlops?  And how do I tell the difference?   What kind of milage can I expect out of TT100's verus something like a BT45 Bridgestone?

I'm in southern Ks, so I'm quite a ways from the mountains and I have to pound down quite a few flat boring miles before I can get to somewhere fun to ride.  Maybe TT100's aren't the right tire for my riding habits

I think the only way to find out: have the dealer read the side of the tire. It says, "Made in..." somewhere, by law.

Although, you may be right about the long, straight rides. 

Thanks, that's kinda what I was wanting to hear.  I was worried that I couldn't sit at the cool table unless I had TT100's

[Andoo]

I love my Bridgestone Battleaxe BT 45's. They are dual compound, so you get good life out of the tire and lots of grip in the corners.

[andy750]

I love my Bridgestone Battleaxe BT 45's. They are dual compound, so you get good life out of the tire and lots of grip in the corners.

+1