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1970 A65L front tire size.
#812414 06/13/20 10:52 pm
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Was down at the motorcycle super store today for a unrelated reason and while I was there I decided to pick up a front tire for the 1970 A65L(the old one is nine years old and beginning to dry rot). Well, I accidentally picked up a 3.50-19 K70 rather than the 3.25-19 K70 currently on the bike. Had planned to return the tire when I decided to look in the owners manual to see what size BSA recommended.

To my surprise, the owners manual has 2 recommended sizes for the front, 3.25-19 ribbed and 3.50-19 K70 while for the rear only 4.00-18 K70. Whats the story here? Were some models shipped with 3.50-19 K70s and some with 3.25-19 ribbed tires? If so, what models came with which? The manual print date is June 1969 and covers the models A50, A65T, A65L and A65FS.

Thanks, Doug


1970 BSA A65L
1974 Yamaha RD350
1975 Honda CB400F
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Re: 1970 A65L front tire size.
Doug Lightfoot #812419 06/13/20 11:24 pm
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I imagine a 3.25x19 is most preferred but I wouldn't have any problem running a 3.50x19 K70.


Jon W.


1957 6T Thunderbird 650
1968 T100R Daytona 500
1971 TR6R Tiger 650
1970 BSA A65F 650
1955 Tiger 100 - Project
1971 BSA A65 650 - Project
1972 Norton Commando 750 "Combat"


"Every time I listen to AC/DC, so do my neighbors"

Re: 1970 A65L front tire size.
Doug Lightfoot #812435 06/14/20 1:31 am
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Venturing a guess here, but I'd think the home models may have used the ribbed, and export/USA the K70? Often in the manuals they'll list both options on parts, but usually mention the application...

But it does surprise me that a 3.50-19 is recommended, that size was generally regarded as a "competition" sized tire I thought.

Last edited by Steve Erickson; 06/14/20 1:34 am.
Re: 1970 A65L front tire size.
Doug Lightfoot #812445 06/14/20 6:48 am
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I believe from reading specs from the time that the 3.50-19 was for either west coast only or all the US Lightning’s. I’ve ran a 3.50-19 on the front and it doesn’t suit the handling as good as the 3.25 does. Made me feel like it wanted to take wider corners. The same tyres on my Canam handled beautifully.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Re: 1970 A65L front tire size.
Doug Lightfoot #812469 06/14/20 12:03 pm
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Here's a little input. My Hornet uses a 3.50x19 as standard. I rode my GS for a while with the 3.50x19 K-70. It worked ok but when I switched to the correct 3.25 the handling was improved. The steering was lighter much as Allan said. However, the 3.50 fills the fender better and looks a bit 'tougher'. Either ok. You decide. Cheers, PRT

Re: 1970 A65L front tire size.
Doug Lightfoot #812547 06/14/20 9:16 pm
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My 1967 Lightning originally came with a 3.25 ribbed tire. I tried a 3.50 something-or-other once (I think it was a Continental), and like Allan and Tom said, I didn't like it as much as the 3.25.

Also, the 3.50 came VERY close to the center fender stays. I've never owned a Hornet or a Spit, but perhaps the compe. models have front fenders that provide a bit more clearance.


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
Re: 1970 A65L front tire size.
Doug Lightfoot #812551 06/14/20 9:47 pm
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Looked through all my manuals(parts, service and owners) and found no correlation to which came with the 3.25 and which with the 3.50. Since my bike is a Lightning and is on the west coast maybe I will try the 3.50. I do like the handling of the 3.25 but it does look a bit small compared to the rear. We will see, I am in no hurry to install it so will have to think about it a bit and decide, thanks for the input guys.


1970 BSA A65L
1974 Yamaha RD350
1975 Honda CB400F
Re: 1970 A65L front tire size.
Doug Lightfoot #812568 06/15/20 12:22 am
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Originally Posted by Doug Lightfoot
I am in no hurry to install it so will have to think about it a bit and decide

Doug, I might be interested in taking it off your hands if the price is right.


Jon W.


1957 6T Thunderbird 650
1968 T100R Daytona 500
1971 TR6R Tiger 650
1970 BSA A65F 650
1955 Tiger 100 - Project
1971 BSA A65 650 - Project
1972 Norton Commando 750 "Combat"


"Every time I listen to AC/DC, so do my neighbors"

Re: 1970 A65L front tire size.
Mark Z #812624 06/15/20 8:59 am
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Originally Posted by Mark Z
My 1967 Lightning originally came with a 3.25 ribbed tire. I tried a 3.50 something-or-other once (I think it was a Continental), and like Allan and Tom said, I didn't like it as much as the 3.25.

Also, the 3.50 came VERY close to the center fender stays. I've never owned a Hornet or a Spit, but perhaps the compe. models have front fenders that provide a bit more clearance.

The later firebird with the triumph forks had a centre stay which was Y shaped to allow the tyre to get closer to the fork leg. I don’t remember clearance being too much of a problem on my 68’ with Beezer forks but I can’t remember how close it came.

A fat tyre looks better on a bike I’ll give it that, but whether you’d have to fit a back tyre which was maybe a 4.25:18 to balance it out.... I’m not sure, it probably doesn’t work out as simply as that.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Re: 1970 A65L front tire size.
Doug Lightfoot #813109 06/19/20 2:46 am
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Ended up returning the 3.5 for a 3.25. Pondered trying the 3.50 but I know I like the 3.25 and decided not to mess with something I know works. Thanks guys!


1970 BSA A65L
1974 Yamaha RD350
1975 Honda CB400F
1 member likes this: Allan G
Re: 1970 A65L front tire size.
Doug Lightfoot #814276 06/28/20 1:19 pm
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The owner's manual that came with my 1968 Thunderbolt from new says 3.25 is the recommended size for ribbed tires, and 3.50 for non-ribbed.


1970 Lightning
1968 Thunderbolt
Re: 1970 A65L front tire size.
Doug Lightfoot #814292 06/28/20 3:21 pm
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You try a 3.50 then use a 3.25 of the same tyre and you’ll use the 3.25.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Re: 1970 A65L front tire size.
Allan G #814296 06/28/20 3:30 pm
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Originally Posted by Allan G
You try a 3.50 then use a 3.25 of the same tyre and you’ll use the 3.25.
Yeah, not questioning that, just sharing what BSA claimed in the manual.


1970 Lightning
1968 Thunderbolt

Moderated by  Allan G, Jon W. Whitley 

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