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Author Topic: Quick tire question  (Read 214 times)

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Offline AlekStooge

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Quick tire question
« on: February 10, 2019, 05:03:01 pm »
I'm rebuilding my wheels. 1978 CB 550K, stock size rim 1.85 front and rear. I found front tire 3.25/100-19 for the back I could do 100/90-18 or save $20 and do 4.00/100-18. The width difference is minuet, I'm thinking of the aspect ratio should I match it to the front or just save the $?

https://www.denniskirk.com/avon/am26-roadrider-tire.pfp543162.prdf

Thanks

Offline Bankerdanny

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Re: Quick tire question
« Reply #1 on: February 10, 2019, 05:53:16 pm »
The 4.00 is too wide. The 750 that tire fits has a 2.15 rear rim. Spend the extra $20 and get the 100/90, it is slightly wider that stock, but will fit the rim fine.
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Current: '76 CB750F, '74 CB550k project bike, '77 CB550F basket case engine donor. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki 80 (K11 probably, it's been 30 years), '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline AlekStooge

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Re: Quick tire question
« Reply #2 on: February 10, 2019, 06:02:48 pm »
It's a 1.6mm difference between the 4.00 and 100? The cost is less for the 100/90...

Offline Stev-o

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Re: Quick tire question
« Reply #3 on: February 10, 2019, 07:29:52 pm »
I put a 4.00 on my 550F....no issue for me. 
'74 "Big Bang" Honda 750K [836].....'71 Honda 750K project.....'76 Honda 550F.....K3 Park Racer.....K5 Fiddy Dolla Special!......CB500 Fiddy Dolla Special too!!............plus plus plus.........

Offline flatlander

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Re: Quick tire question
« Reply #4 on: February 10, 2019, 11:15:58 pm »
#me too

Offline brewsky

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Re: Quick tire question
« Reply #5 on: February 11, 2019, 02:33:30 am »
Me 3....'78 550K
Match front and back....either inch or metric for both
3.25-19 and 4.00-18 handle perfectly
« Last Edit: February 11, 2019, 03:21:40 am by brewsky »
66 CA77
78 550K
78 CB750K
02 FZ1
09 GL 1800

Offline TwoTired

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Re: Quick tire question
« Reply #6 on: February 11, 2019, 10:59:40 am »
I've been using 3.25 19 fronts and 4.00 18 rears on my 550s for 30 years.  No regrets. I did try metrics out a while back.  But, went back to inch sizes.

I think the stock rear was 3.75, 18  which isn't easy to find these days.  (Or necessary, imo.) 

The inch sizes are more apt to have the aspect ratio profile (100%) that was used in the suspension design, rather than metric sizes which use, at best, a 90% ratio.  But, tire manufacturer do take liberties.

I've been happiest with Metzelers, so far.

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

 

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