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Author Topic: Tire Recommendations for CB750K1  (Read 3644 times)

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Offline RustyJC

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Tire Recommendations for CB750K1
« on: July 11, 2011, 07:15:53 AM »
I hope to have my 1971 CB750K1 running this coming weekend.  I should get the fuel tank back from being cleaned and sealed this week (see below).  After getting it inspected and licensed, the first order of business is to replace the weather-checked Dunlop TT100s now on the bike that were installed in the early 1970s.  :o

What modern tires are available to fit the spoked 19" front (3.25-19 original tire size) and 18" rear (4.00-18 original tire size) rims fitted to this bike?  On my 2007 BMW, I would use a tire like the Michelin Pilot Road or the Dunlop Roadsmart (currently fitted) - a "sport touring" tire that is a compromise between handling the twisties and reasonable tire life.  I'm looking for something similar for the CB750.

Suggestions???  Experiences???  Sources???

Thanks for your valued input.

Rusty
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1971 CB750K1 (original owner)

2007 BMW K1200GT

Offline Duke McDukiedook

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Re: Tire Recommendations for CB750K1
« Reply #1 on: July 11, 2011, 07:42:00 AM »
Coker tire produces firestone replicas that look pretty authentic to the original if that is what you are going for. A lot of people go with Bridgestone Spifires for these bikes. Pretty much whataever you go with you will want to go with a symmetrical blocked rear and a ribbed front tire, that is what was originally used.
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Offline Bankerdanny

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Re: Tire Recommendations for CB750K1
« Reply #2 on: July 11, 2011, 08:02:34 AM »
Plenty of modern options. Just hit the major retail sites (BikeBandit, Motorcycle-superstore etc) and enter the sizes.

Avon, Bridgestone, Dunlop, Continental and Michelin all have tires in multiple models that will fit the 750, although you may need to go to a metric size for the rear as 4.00-18 is not always available. Each tire should list the rim specs needed. Know your rim sizes and make sure that the tire you are considering works with the rim widths on your bike.

I'm going to disagree with ISD though, unless period appearance is important there is no reason to go with the old fashioned ribbed look. It will severely limit your tire options, and there is a reason that none of the manufacturers put a ribbed front on their bikes now.

Stay away from radials too. They generally require a wider rim than an identically sized bias ply.
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Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline RustyJC

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Re: Tire Recommendations for CB750K1
« Reply #3 on: July 11, 2011, 08:08:42 AM »
Looking at the Bridgestone Spitfires, it appears that the 90/90H-19 front (3.25 inches actually equates to 82.55 mm) and 110/90H-18 rear (4.00 inches actually equates to 101.6 mm) would be the closest metric match.  Are these the metric sizes generally used as replacements for the 3.25-19 and 4.00-18??

Rusty
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1971 CB750K1 (original owner)

2007 BMW K1200GT

Offline Johnie

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Re: Tire Recommendations for CB750K1
« Reply #4 on: July 11, 2011, 08:17:13 AM »
I have Continentals and here is a pic of the tread pattern for you. I mainly went with those as that was the consensus of the board a while ago. I am very happy with all 3 sets. Click pic to enlarge it...
« Last Edit: July 11, 2011, 08:19:06 AM by Johnie »
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1976 GL1000 Sulphur Yellow

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Offline RustyJC

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Re: Tire Recommendations for CB750K1
« Reply #5 on: July 11, 2011, 08:49:08 AM »
Motorcycle Superstore is recommending 100/90H-19 and 110/90H-18 to replace the 3.25-19 and 4.00-18 respectively.  That 100 mm section width on the front looks pretty wide - it actually converts to 3.937 inches.  Comments?

Rusty
« Last Edit: July 11, 2011, 08:51:59 AM by RustyJC »
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1971 CB750K1 (original owner)

2007 BMW K1200GT

Hinomaru

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Re: Tire Recommendations for CB750K1
« Reply #6 on: July 11, 2011, 09:05:04 AM »
+1 on the Continental tires
 
The Continental RB2 / K112 are not modern high performance tires, but certainly up to their task. They offer excellent all around handling, wet & dry traction and braking along with the original OEM look. Nice choice for stock vintage 1969-76 CB750 K model bikes. They come in the original correct sizes: 3.25 X 19 front and 4.00 X 18 rear. The only downside (for me) is that they are sensitive to rain grooves causing the bike to wander.
 
http://www.conti-online.com/generator/www/de/en/continental/motorcycle/themes/motorcycletires/sport_classic/k112_rb2/k112rb2_en.html

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Offline andy750

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Re: Tire Recommendations for CB750K1
« Reply #7 on: July 11, 2011, 09:12:55 AM »
You cant go wrong with Bridgestone BT-45s....great handling in rain/dry/gravel and excellent in corners. Use at 110/90/18 and 100/90/19 for best results. A 120 on the back can result in cupping on stock rims

Here is a front wheel comparison between Dunlop K70s and Bridgeston BT-45s.



Dunlop K70 for the front:



BT-45 on the back...110 V 120







good luck
Andy

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Current bikes
1. CB750K4: Long distance bike, 17 countries and counting...2001 - Trans-USA-Mexico, 2003 - European Tour, 2004 - SOHC Easy Rider Trip , 2008 - Adirondack Tour 2-up , 2013 - Tail of the Dragon Tour , 2017: 836 kit install and bottom end rebuild. And rebirth: http://forums.sohc4.net/index.php/topic,173213.msg2029836.html#msg2029836
2. CB750/810cc K2  - road racer with JMR worked head 71 hp
3. Yamaha Tenere T700 2022

Where did you go on your bike today? - http://forums.sohc4.net/index.php?topic=45183.2350

Offline RustyJC

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Re: Tire Recommendations for CB750K1
« Reply #8 on: July 11, 2011, 09:15:51 AM »
Quote from: Hinomaru on July 11, 2011, 09:05:04 AM
The only downside (for me) is that they are sensitive to rain grooves causing the bike to wander.
 

That's a pretty big downside for me as we have a LOT of rain-grooved freeway overpasses in the Houston area.  That's what I would expect with a ribbed front tire, however.

Rusty
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1971 CB750K1 (original owner)

2007 BMW K1200GT

Offline RustyJC

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Re: Tire Recommendations for CB750K1
« Reply #9 on: July 11, 2011, 11:21:51 AM »
Tires, tubes and rim bands ordered.  Thanks to all who posted for the help.

Rusty
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1971 CB750K1 (original owner)

2007 BMW K1200GT

Offline Chase Rhodes

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Re: Tire Recommendations for CB750K1
« Reply #10 on: August 16, 2011, 02:08:29 PM »
I also own a 1971 CB750K1 and found that Motorcycle Superstore sells Dunlop Retro tires that match the old factory 3.25-19 front and 4.00-18 rear.  They look great and ride fine.  About $125 for the pair with free shipping.

 
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