Honda CB750 Sandcast

TYRES, TIRES and RUBBER - FITTED to EARLY CB750's

kp · 26 · 5193

kp

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Hey Everybody! Can we get as much feedback from registered members as we can on this topic. Whilst the subject has been discussed over the years in general restoration threads, I can't actually find a specific thread on this subject.
Who can comment on what tyres were fitted to the early Honda CB750. I have several front rims that have Nitto brand tyres fitted and I believe one of these is an original, but not certain.
Please, please, please add your comment, thoughts, feedback or recollections.
Yabba Dabba KP


bojje

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Hi!
My first CB750, a K0, VIN 24xxx, I purchased in 1970 had Dunlops like them you can buy from Yamiya. Pretty many of my sandcasts had same Dunlop front tyres when they arrived to me. Only one had its original rear tyre, also a Dunlop K87. This is the only I can support you with.
Best Regards Kerry and a Merry  Christmas, Bo from Sweden.


Steve Swan

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Hi!
My first CB750, a K0, VIN 24xxx, I purchased in 1970 had Dunlops like them you can buy from Yamiya. Pretty many of my sandcasts had same Dunlop front tyres when they arrived to me. Only one had its original rear tyre, also a Dunlop K87. This is the only I can support you with.
Best Regards Kerry and a Merry  Christmas, Bo from Sweden.

Thank you Bo and KP, as always, for your contributions keeping this forum alive and well. 

i wonder if Dunlop tires were fitted to machines exported to Europe due to contractual agreements with Dunlop since they were out of Ireland (U.K.) and Bridgestone tires fitted for export to North America? 


bojje

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Hi.
Pretty many of my sandcasts are imported to Sweden from USA and most of them had Dunlop front tyres. Only one, also US bike, had its original rear tyre. Also a Dunlop, a K87.
Bo


hondasan

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CB750-1008054 (9/69 on VIN plate) still had its original Dunlop Gold Seal F7 front tyre fitted when purchased in 2010. It came from the USA.


Chris R
Chris R.
302/338


markb

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i wonder if Dunlop tires were fitted to machines exported to Europe due to contractual agreements with Dunlop since they were out of Ireland (U.K.) and Bridgestone tires fitted for export to North America?  

The 69.4 parts list shows both Bridgestone and Dunlop tires so maybe Honda used whatever was available to them at any given time.

Pretty many of my sandcasts are imported to Sweden from USA and most of them had Dunlop front tyres.

Dunlop may have been a more popular replacement if it was cheaper or better.

Only one, also US bike, had its original rear tyre. Also a Dunlop, a K87.

Just curious, how do you know for sure that it was the original tire, oops, tyre?

I have a question about the K87. The parts list specifically shows the Dunlop K87 as on option for the rear. Do we know that the K87 of today is exactly the same as the K87 of 1969? I have a new K87 and it just seems too big.  

I believe that the Bridgestone tires that were used were the Superspeeds. I haven't found any available tires that look close to the BS front tire with the distinctive straight ribs, which I think is part of the signature look of the CB750. I wish there was a contemporary replacement. That's why I'm thinking of putting a set of used, but not too badly, Bridgestones on #97 just for the correctness (just for show, not riding). If anyone had a set that looked better than the ones I have I would buy them. I guess what I'm saying is I'm still looking for a decent (better) set.

CB750-1008054 (9/69 on VIN plate) still had its original Dunlop Gold Seal F7 front tyre fitted when purchased in 2010. It came from the USA.

Does it look like the Bridgestone Superspeed front and how did you know it was the original?
Mark B
1969 CB750 sandcast #97 restored - Sold Restoration thread link
1969 CB750 sandcaxt #576 - Sold
1969 CB750 sandcast #1553 - Sold
1969 CB750 sandcast #1990 - Sold
1969 CB750 sandcast #5383 restored - Sold Restoration thread link
1970 CB750 K0 restored - Sold
2010 H-D Tri Glide Ultra Classic (Huh?)



hondasan

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How do I know front tyre on 1008054 was its original?
Other than carb tops and rear tyre, bike appeared to be as it left the factory in every respect. Recorded mileage of 10,836, front tyre worn to about 1mm of tread depth and very badly perished on side walls / between treads. Tyre therefore very old, and so likely JUDGED to be original based on overall patina of bike it was on. You are of course correct that I cannot KNOW!
I believe tread pattern is very similar to the Bridgeston equivalent, but do noy have one of those to compare directly with.

Chris R.
Chris R.
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markb

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How do I know front tyre on 1008054 was its original?

Chris, just so you know, I wasn’t challenging your opinion. What you say is logical. I’ve had many times where I wondered if something was original or not.

I’m pretty sure that the Bridgestone tires used on the early CB750s were the Superspeeds. Can anyone confirm this?


Here’s a pic of the tread on the BS front tire. Does it look anything like the Dunlop?

Mark B
1969 CB750 sandcast #97 restored - Sold Restoration thread link
1969 CB750 sandcaxt #576 - Sold
1969 CB750 sandcast #1553 - Sold
1969 CB750 sandcast #1990 - Sold
1969 CB750 sandcast #5383 restored - Sold Restoration thread link
1970 CB750 K0 restored - Sold
2010 H-D Tri Glide Ultra Classic (Huh?)


hondasan

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Looks pretty similar to the Dunlop that I can see.

I also have a really nice rear wheel from a K2, which appears to have its original tyre still fitted - and that one is a Bridgestone Super Speed R2.


Chris R.
Chris R.
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markb

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Yes I agree that Bridgestones were used but my question was were the Superspeeds used on sandcasts.
Mark B
1969 CB750 sandcast #97 restored - Sold Restoration thread link
1969 CB750 sandcaxt #576 - Sold
1969 CB750 sandcast #1553 - Sold
1969 CB750 sandcast #1990 - Sold
1969 CB750 sandcast #5383 restored - Sold Restoration thread link
1970 CB750 K0 restored - Sold
2010 H-D Tri Glide Ultra Classic (Huh?)



markb

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Maybe Superspeeds were all Bridgestone made back then so maybe it's a stupid question. I don't know. Just trying to confirm that is was the Superspeeds used on Sandcasts.  :)
« Last Edit: December 26, 2018, 01:40:00 pm by markb »
Mark B
1969 CB750 sandcast #97 restored - Sold Restoration thread link
1969 CB750 sandcaxt #576 - Sold
1969 CB750 sandcast #1553 - Sold
1969 CB750 sandcast #1990 - Sold
1969 CB750 sandcast #5383 restored - Sold Restoration thread link
1970 CB750 K0 restored - Sold
2010 H-D Tri Glide Ultra Classic (Huh?)


Steve Swan

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Mark, these are good questions.  i would not say they are stupid.  Probably some research into the manufacturing history of these Dunlop and Bridgestone tire companies would be helpful.  what i remember when i got back from my trip to California early June 1970, the tire and chain were both gone; the dealer did not have the chain or tire designed for the 750 and he told me he could not sell me a tire or chain that the factory did not recommend.  as i recall i had roughly 4,000 miles on the odometer.  i have NO idea what tire was on 4779 from factory new; what i do know is a tire specific for the CB750 was unavailable in California (the dealer at Vallejo told me he had no tire (or chain) for the CB750 and therefore to not ride high speeds on the way home from California to Nebraska.)

Sometime  around the time the CB750 was to begin production, the factory had their undies in a wad with the motorcycle manufacturing section of Bridgestone; it is fact that Honda told Bridgestone they'd quit buying tires if Bridgestone didn't quit making motorcycles. my understanding is the Honda factory had the chain and rear tire manufactured to spec to meet the until then unheard of performance the CB750 was capable of.  and i have that memory of Art Olsen at Olsen Brothers Honda/Triumph, Sioux City, Iowa telling me i would have to wait for a chain and a tire for 4779; given Art saying i would have to wait for a tire and chain tells me that tires and chains fitted to Trident's were not suitable for the CB750.  (Art had Trident's on the showroom floor and if i recall correctly both Trident's and Rocket III's were fitted with K70 front and K81 rear.  the K81, if i understand correctly, was designed specifically for the Commando and the triples...)

maybe asking other questions such as the following could shed some light on if Superspeeds were on early sandcast vins...  "What evidence exists that Superspeeds were fitted to early vin sandcasts?  "What dates did these special Dunlops and Bridgestone tires first become available?"  "Was the relationship between the two factories (Bridgestone motorcycles) so strained that Honda was not at the time purchasing tires from Bridgestone?"  "Did demand for the Superspeed exceed supply?" -or- "Was Bridgestone even fully tooled up to begin production of Superspeeds prior to or very early during CB750 production?"  

Mark, your questions are on target. if i understand correctly i think your question is, "Were Superspeeds were fitted to the very early CB750 sandcast vins?"  Another question could be "What is the earliest sandcast vin that a Superspeed tire is found on a sandcast vin?"  However, finding answers to other questions such as i pose might answer your primary question.