Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: Graeme77 on March 08, 2015, 03:03:26 PM
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I need to get new tyres for my f1. Its pretending to be older than it is, ace bars, k rear mudguard, single seat etc so I was looking at maybe k81 dunlops for it but the sizes are confusing my.
Would 3.60x19 and 4.25/85x18 be right?
It currently has 100/80 and 120/80 on it so something this sort of size would be nice.
Ive looked at size conversions but why do these have a decimal point and is 4.21/85 a tyre wall ratio like metric tyres?
Im finding it hard to choose tyres but I think it will either be these k81s or ill have to go more modern with metzler/roadrider/bt45 or suchlike.
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tyre sizes can be confusing,
your front,3.60 - ? X 19,is normally a 3".60 inch wide and most cases a 90% profile ratio,X 19" diameter,
try to figure,also check the overall diameter,http://www.avon-tyres.co.uk/motorcycle/roadrider
these are my personal favorite tyres,they grip very well,and help the bike to feel light and small,
what size is in the hand book?
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If you are looking for old style, Avon AM6 and AM7's are available at a good price. If you are on about F1 CB750 i have just put 3.25-19 on the front and 4.00-18 rear from Mytyres.
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Yes, its a 750. Book is in the loft so just looked sizes up. As you say, 3.25 19 and 4.00 19.
Do they not look a little small?
I was going to get avons but ive read alot of bad opinions on the safety milage rear. Ive read good stuff too though.
I have a gsxr if I want all out handling, but I do like a nice sweeping corner :)
I found a thread on here recomending 4.10 19 and 4.25/85 18 if getting the k81's.
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Does a k70 rear work ok with a speedmaster front?
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Yes, its a 750. Book is in the loft so just looked sizes up. As you say, 3.25 19 and 4.00 19.
Do they not look a little small?
I was going to get avons but ive read alot of bad opinions on the safety milage rear. Ive read good stuff too though.
I have a gsxr if I want all out handling, but I do like a nice sweeping corner :)
I found a thread on here recomending 4.10 19 and 4.25/85 18 if getting the k81's.
4.10-19 on the front? the forks are not that wide. You will find it very hard to find a 4.25-18 for the rear, or is it 4.10 ? A GSXR is not a CB750 ;D
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Just noticed you have 80 wall tyres on, which is a low profile type for a CB750. The modern tyre should have a 90 wall.
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Hi Graeme I've just fitted Dunlop TT100's to my 750 and my Kettle , got my tyres from www.vintage-tyres.co.uk front is 4.10x19 rear is 4.25/85x18,
cheers Mick.
(http://i234.photobucket.com/albums/ee75/mcpuffett/003_zps9f524f39.jpg) (http://s234.photobucket.com/user/mcpuffett/media/003_zps9f524f39.jpg.html)
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Hi Graeme I've just fitted Dunlop TT100's to my 750 and my Kettle , got my tyres from www.vintage-tyres.co.uk front is 4.10x19 rear is 4.25/85x18,
cheers Mick.
(http://i234.photobucket.com/albums/ee75/mcpuffett/003_zps9f524f39.jpg) (http://s234.photobucket.com/user/mcpuffett/media/003_zps9f524f39.jpg.html)
It must be 4.10-18 that are hard to find these day Mick
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Yes, its a 750. Book is in the loft so just looked sizes up. As you say, 3.25 19 and 4.00 19.
Do they not look a little small?
I was going to get avons but ive read alot of bad opinions on the safety milage rear. Ive read good stuff too though.
I have a gsxr if I want all out handling, but I do like a nice sweeping corner :)
I found a thread on here recomending 4.10 19 and 4.25/85 18 if getting the k81's.
4.10-19 on the front? the forks are not that wide. You will find it very hard to find a 4.25-18 for the rear, or is it 4.10 ? A GSXR is not a CB750 ;D
people do seem to fit 4.10 19 and 4.25/85 18 on cb750's.
My comment about the gsxr was saying necausebibhave that im not after getting every last drop of ability out of the cb. The cb is for more relaxing journeys.
Oh, and I mistuped. The current tyres are 90 profile not 80.
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Mick, have you got any photos of them fitted to the cb? I am still favouring tt100 just not sure in which sizes.
I think the 4.10/19 and 4.25/85/18 will be closer to whats on it now.
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A 4.10-19 on the front will not work on a CB750 unless the mudguard is removed and the forks widened. Look at the link that Mick has provided and enter CB750F for the tyres they recommend for the F1. Is this a cafe/custom F1?
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Trigger both front tyres are 4.10 x19 got those off an ebay seller and got my 2 rear tyres from vintage tyres , I've been running TT100's on both my F1 and k model with no probs or modifications ? cheers Mick, ;)
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Its slightly cafe/custom but apart from the rim the front end is all stock.
aparantly the 4.10/19 is 108mm wide. The 3.60/18 is 93mm wide.
I am not trying to go wider on the front for looks or anything, just trying to work out whats going to be best and nearest in size to my 100-90/19.
So if its 3.60/19 on the front would you put 4.10/18 or 4.25-85/18 on back?
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Trigger both front tyres are 4.10 x19 got those off an ebay seller and got my 2 rear tyres from vintage tyres , I've been running TT100's on both my F1 and k model with no probs or modifications ? cheers Mick, ;)
So 4.10/19 does fit?
Have you tried the smaller sizes of tt100 and prefered the larger?
edit..
vintage tyres recomend 3.60/19 front and 4.25-85/18 rear.
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Hi Graeme , I've always used 4.10x19 and had no issues , my bike probably had them on when I got it back in 1992 ?, so I've just changed them like for like ?, I havn't tried the smaller size, but I have tried Dunlop Goldseal k70's as they were cheaper than TT100's they were a smaller size I think they were 3.50x19 front and 4.00x18 rear , i'll have a look for a photo of my F1 with TT 100's fitted I've plenty of my KO , cheers Mick ;)
(http://i234.photobucket.com/albums/ee75/mcpuffett/tyres009.jpg) (http://s234.photobucket.com/user/mcpuffett/media/tyres009.jpg.html)
(http://i234.photobucket.com/albums/ee75/mcpuffett/tyres011.jpg) (http://s234.photobucket.com/user/mcpuffett/media/tyres011.jpg.html)
(http://i234.photobucket.com/albums/ee75/mcpuffett/tyres004.jpg) (http://s234.photobucket.com/user/mcpuffett/media/tyres004.jpg.html)
(http://i234.photobucket.com/albums/ee75/mcpuffett/tyres007.jpg) (http://s234.photobucket.com/user/mcpuffett/media/tyres007.jpg.html)
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Thanks. The photos help alot. Ill compare your pics with my bike and see what I think.
I quite like a skinny looking front but dont want it to look lost under the mudguard.
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Original sizes for the 750 eqate to 4.10 x 19 front and 4.25/85 x 18 rear, these replaced 3.50 x 19 front and 4.00 x 18 rear
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I found these 2 photos of both my F1's fitted with 4.10X19 TT 100's ;) cheers Mick.
(http://i234.photobucket.com/albums/ee75/mcpuffett/dads%20pics%20028_zps29n6kvxz.jpg) (http://s234.photobucket.com/user/mcpuffett/media/dads%20pics%20028_zps29n6kvxz.jpg.html)
(http://i234.photobucket.com/albums/ee75/mcpuffett/dads%20pic%20024_zpsleszxl2s.jpg) (http://s234.photobucket.com/user/mcpuffett/media/dads%20pic%20024_zpsleszxl2s.jpg.html)
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I still think Continental RB'2 on the front and K112 on the rear are the best looking tyres and they give enough grip for scratching. ;)
Mick
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Gold Seals? I shunned these when I was riding a 250, everyone did.
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I'm using conti's on my 750's and have found them by far the best....http://pages.ebay.com/link/?nav=item.view&alt=web&id=141594993228
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Just looked up the conti's. They look good.
Is 3.25/19 not a bit small for the front though?
I also found avon roadrunner f2 and r2. Seems they are race compound though. Doesnt bother me but dont know if they are road legal and cant find anywhere that sells them.
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In theory it should turn in faster on the skinnier tyre I push my bike fairly hard and will use it in the rain I'v not had any scary moments to date.
Mick
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Just looked up the conti's. They look good.
Is 3.25/19 not a bit small for the front though?
I also found avon roadrunner f2 and r2. Seems they are race compound though. Doesnt bother me but dont know if they are road legal and cant find anywhere that sells them.
Those are the factory specified sizes as far as I'm aware.
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I'm using conti's on my 750's and have found them by far the best....http://pages.ebay.com/link/?nav=item.view&alt=web&id=141594993228
Nice choice James look like a good compromise with the style of the original K series tyres.
Wonder why the listing ended early?
Ash
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Well it seems im going with bt45's in the end anyway.
Also, looking at bridgestones info the 3.25 19 and 100/90 19 measure up almost the same somehow.
I dropped the wheels of today, just waiting for a price.
No rush as my frame is off being powder coated at the moment anyway.
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i was about to ask what would be the best tyre for a bit of scratching but Green1 just came up with the answer. i just want the most modern grippiest tyre i can get.
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I reccommend the Avon AM 26 roadriders,
I use 3.25 x 19 F and 4.00 x 18 rear,
this is for my little 500,but they make the feel nimble and light !!
and grip very well
I run 28 psi F and 33 psi rear
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The Conti's aren't the most modern but a good compromise.There a mid 70's design but made from a modern compound.
The Roadriders and bt45's look a bit to modern for my liking.
Mick
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ok thanks. bt45 it is then!
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There is something about the rear continentals tread I dont like.
The tyre guy said he's had a few customers who's roadriders had cracked if the bike wasnt regularly riden so he recomended the bt45's.
I was leaning towards them or the k81, in the end I went with performance over style.
Will be a while till its back in one piece but cant wait to get it back on the road :)
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I too have heard of the roadriders cracking.
I think the Conti's look beater on the bike than off.
Mick
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I have flanged alloy rims so I dont know stock size but my rear rim is 2.15.
Cant remember what the front is and the wheels are at the tyre fitters.
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The sizes Oddjob quotes were the standard size for the 750 that had the wider rims, 500 should use 3.60 x 19 on the front and 4.10 x 18 on the rear
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I thought all the 750 had wider rims as they came standard with 3.50 front and 4.00 rear tyres mate
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Pretty sure the factory fitment on all 69-76 K models was 3.25*19 & 4.00*18?
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You are right according to the parts book 750 was 3.25 front and 4.00 rear the 500 was 3.25 bfront and 3.50 rear. The Guiness must have attacked the grey cells again, i always thought the 750 was bigger on both but perhaps we just fitted bigger!!
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You are right according to the parts book 750 was 3.25 front and 4.00 rear the 500 was 3.25 bfront and 3.50 rear. The Guiness must have attacked the grey cells again, i always thought the 750 was bigger on both but perhaps we just fitted bigger!!
:-) I've had a couple of bikes arrive from the us with 3.50 on the front & 4.25 on the rear and they handled like sh*te - in my opinion the factory spec sizes are spot on.
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Rims are stamped with width so should be easy for the 750 owners to check. It may be that they stayed unchanged until the F1/F2 when the Comstars were fitted, those were certainly wider than the spoked versions.
Considering how anal :) the K0 owners are about DID rims I'm surprised one of them hasn't been on to tell us the exact rim size.
original rear K0 rim D.I.D. 2.15 X 18 (JUST GOT MY FINGER OUT :) )
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You are right according to the parts book 750 was 3.25 front and 4.00 rear the 500 was 3.25 bfront and 3.50 rear. The Guiness must have attacked the grey cells again, i always thought the 750 was bigger on both but perhaps we just fitted bigger!!
:-) I've had a couple of bikes arrive from the us with 3.50 on the front & 4.25 on the rear and they handled like sh*te - in my opinion the factory spec sizes are spot on.
+1 on that James. Lots of people think that putting wider tyres on will improve the handling but, it does not
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I fit a 4.00 wide rear because 3.50 is not available,
it increases the gearing,cured by a 1 tooth smaller gearbox sprocket,
and by running at 33psi,instead of 36 reccommended) it handles like a gem,it also increases ride height,
but handles really good,
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John, if you're running a 750 K bike ('69-76) then 4.00 *18 rear is the factory specification tyre....
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John, if you're running a 750 K bike ('69-76) then 4.00 *18 rear is the factory specification tyre....
James,It's a 'umble 500,hence the 3.50 as standard,
but thanks for the info
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John, if you're running a 750 K bike ('69-76) then 4.00 *18 rear is the factory specification tyre....
James,It's a 'umble 500,hence the 3.50 as standard,
but thanks for the info
Ahh got ya. Nothing humble about the 500/4 - awesome machines imho...
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Hi Graeme I've just fitted Dunlop TT100's to my 750 and my Kettle , got my tyres from www.vintage-tyres.co.uk front is 4.10x19 rear is 4.25/85x18,
cheers Mick.
(http://i234.photobucket.com/albums/ee75/mcpuffett/003_zps9f524f39.jpg) (http://s234.photobucket.com/user/mcpuffett/media/003_zps9f524f39.jpg.html)
Back in the 1970s, the first thing we did after buying a brand new CB500 four was to change the tyres for TT100s - they made a world of difference.
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What happened to all the tyres you removed?