Author Topic: Cheap Bastid Tire Question  (Read 2577 times)

Online SmithSwede

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Cheap Bastid Tire Question
« on: May 12, 2016, 06:39:45 PM »
My 2013 Stone calls for a 130/80-17 rear tire. 

However, I have a goodly supply of 130/70-17 tires meant to be used on a Ninja 250, which doesn't get ridden as much now that I have a Guzzi.

So the cheap bastid gears in my brain start turning. 

80% of 130 = 104mm. 70% of 130 is 91 mm.  Difference of 13mm, doubled, is 26mm, which is basically an inch. 

Does a 1" difference in sidewall height really make a difference.  Don't care about speedometer accuracy.  Not racing at Isle of Man.  Just trying to figure out if it would be a Really Dumb Idea to use 130/70 on the Guzzi, or if that's a non-crazy way to use up tires, providing I ride in a same manner.

Thoughts?
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Offline travelingbyguzzi

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Re: Cheap Bastid Tire Question
« Reply #1 on: May 12, 2016, 07:01:13 PM »
It will put your bevel box 1/2" lower so it will increase the chance of gear oil migrating from tranny to bevelbox. Also might slow the steering a bit as it will increase rake. The fix for both of these situations is to slide the forks up through the tripleclamps 1/2".
On the plus side, will lower the gearing a bit for better acceleration.
If I had the tire sitting around, I would use it.
If my thinking is wrong, someone will tell us.
Bill
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Offline PJPR01

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Re: Cheap Bastid Tire Question
« Reply #2 on: May 12, 2016, 07:41:43 PM »
P... - I would bundle up those tires and sell them on Ebay for a fair discounted price, and then just go and get the right set of tires...

:)
Paul R
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oldbike54

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Re: Cheap Bastid Tire Question
« Reply #3 on: May 12, 2016, 08:08:54 PM »
 OK Jay , frugality is one thing , but geez  :laugh:

 Dusty

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Re: Cheap Bastid Tire Question
« Reply #3 on: May 12, 2016, 08:08:54 PM »

Offline Arizona Wayne

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Re: Cheap Bastid Tire Question
« Reply #4 on: May 12, 2016, 08:28:06 PM »
Only thing I would wonder about is if the rim width is OK for the 130/70 tire.  It would definitely make your bike lower and gearing lower.  I've gone the opposite route putting a 130/90 rear tire on my 750 Breva instead of a 130/80 to make the gearing 250 rpm taller.   So in y0ur case you would probably make your gearing 250 rpm lower.

Online jcctx

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Re: Cheap Bastid Tire Question
« Reply #5 on: May 13, 2016, 10:02:20 AM »
Unless you measure the difference in the two mounted air up tires you are just guessing as the difference in manufacturing can  be bigger than the stated actual!!

Offline rocker59

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Re: Cheap Bastid Tire Question
« Reply #6 on: May 13, 2016, 10:10:45 AM »
An interesting side note:  1997 Sport 1100i had a 160/70-17 rear.  The Daytona RS had a 160/60-17.  Chassis was identical.

No , your V7 will not know the height difference in a 130/70 and a 130/80.  The slightly shorter tire will cause some speedo error, if your bike's speedo is driven off the transmission.  Steering geometry will change, which might slow the steering a little bit, but you could counteract that with dropping the front end.

Otherwise, no big whoop...
Michael T.
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Offline Zinfan

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Re: Cheap Bastid Tire Question
« Reply #7 on: May 13, 2016, 10:39:09 AM »
I'd make sure the load and speed rating of those tires will work with the V7, I don't think the size difference is much to worry about.

Offline Triple Jim

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Re: Cheap Bastid Tire Question
« Reply #8 on: May 13, 2016, 10:41:16 AM »
Rear tires don't last terribly long.  I'd use them.  The differences are well described above, and are minor.  Either that or ride the 250 more.  :)
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Online SmithSwede

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Re: Cheap Bastid Tire Question
« Reply #9 on: May 13, 2016, 09:10:30 PM »
Thanks everyone.   Seems like no biggie, besides the obvious minor downsides. 

I'll probably give this a try when my current tire is "square and bare."
Accentuate the positive;
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Latch on to the affirmative;
Don't mess with Mister In-Between.

Offline n3303j

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Re: Cheap Bastid Tire Question
« Reply #10 on: May 13, 2016, 10:30:54 PM »
How old are the tires you want to mount?
Over 5 years I'd dispose of them.
'98 MG V11 EV
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Offline Triple Jim

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Re: Cheap Bastid Tire Question
« Reply #11 on: May 13, 2016, 10:38:59 PM »
How old are the tires you want to mount?
Over 5 years I'd dispose of them.

How degraded a tire is after five years really depends on how it's stored.  Outdoors in direct sunlight, you're probably right.  Indoors, out of UV and temperature extremes, they're probably not much different from new.
When the Brussels sprout fails to venture from its lair, it is time to roll a beaver up a grassy slope.

Offline n3303j

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Re: Cheap Bastid Tire Question
« Reply #12 on: May 13, 2016, 11:09:05 PM »
Bought a class C motor home with 7 year old tires on it. They were quality name brand and of the proper rating for the vehicle. They were over 90% UNWORN and looked beautiful. There wasn't a sign of weathering or ageing anywhere to be seem on the tires. Except for the date code they could pass for new.

Told the seller that I'd need tires really soon based on the date code and received a price adjustment.

By the time we reached Texas (about 2,000 miles) four of the six tires had delaminated sufficiently that the vehicle  (which never saw  over 55 mph on my watch) rode with a constant quiver. Tire shop put the wheels on the balancing machine and hand spun each. The "hops" were easily visible with the naked eye. 4 out of 6 is a pretty significant figure. So arbitrarily I replace tires that have had their 5th birthday. On my bikes I wear them out long before 5 years so it's not an issue. But the V11EV I recently bought came with a 7 year old on the front. Looked okay, handled like crap. Trash guy took it away Wednesday. Bad handling disappeared.
'98 MG V11 EV
'96 URAL SPORTSMAN
'77 MG 850T3 FB

Offline Arizona Wayne

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Re: Cheap Bastid Tire Question
« Reply #13 on: May 14, 2016, 12:29:16 AM »
How degraded a tire is after five years really depends on how it's stored.  Outdoors in direct sunlight, you're probably right.  Indoors, out of UV and temperature extremes, they're probably not much different from new.


I'm with you on this, but many here don't want to here this.  They've been brainwashed by tire companies.   :lipsrsealed:

Online SmithSwede

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Re: Cheap Bastid Tire Question
« Reply #14 on: May 14, 2016, 08:45:48 AM »
These are only 18 months old.  Stored indoors and even air conditioned.
Accentuate the positive;
Eliminate the negative;
Latch on to the affirmative;
Don't mess with Mister In-Between.

Offline n3303j

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Re: Cheap Bastid Tire Question
« Reply #15 on: May 14, 2016, 08:54:47 AM »
These are only 18 months old.  Stored indoors and even air conditioned.
That's almost as new as they can get.
'98 MG V11 EV
'96 URAL SPORTSMAN
'77 MG 850T3 FB

Offline travelingbyguzzi

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Re: Cheap Bastid Tire Question
« Reply #16 on: May 14, 2016, 09:01:38 AM »
Just this week, I took a 10 yr old Dunlop with 15K miles off of my Eldo. Not because it was terribly worn, but because it had a 1 1/2" sheetmetel screw in it. I had already decided it was time to replace, but the screw ended my procrastination.
73 Eldorado
80 Sp
85 Cal II
97 1100Sport
08 1200 Sport AKA:Sweet Leaf
I'm not really drowning; I can see the beach from here.

Offline Murray

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Re: Cheap Bastid Tire Question
« Reply #17 on: May 14, 2016, 09:37:02 AM »
Just make sure you don't end up mixing an radial tyre with a more traditional cross ply which are still available in more traditional sizes you won't like the handling results.


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