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Tyre size switching: how will it go?
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@subetherbass avatar
SubEtherBASS
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1997 Italjet Formula 125, 2 matching N.Z. '69 VBC Super, 177cc Racer, VespaCross Bodge, Puch SRA150, Piaggio Zip 100! & others
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SubEtherBASS
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1997 Italjet Formula 125, 2 matching N.Z. '69 VBC Super, 177cc Racer, VespaCross Bodge, Puch SRA150, Piaggio Zip 100! & others
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UTC quote
My Zip 100 4t has Malossi Variator kit, pod air filter & (soon) a 125 exhaust (looks original, just bigger)...

I'm thinking of changing the REAR tyre from 120/70-10 to 120/90-10

Specs & differences are in pic.
Does anyone have experience with tyre size changes?
Forum member supplied image with no explanatory text
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UTC quote
If you've got a friend who has a scooter with the 120/90-10 tire either on front or in back, take the time to see if it will fit before you buy and mount one on your rim. You might not have the room.
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WLeuthold
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UTC quote
On my Vespa GTs, I have been running 140/70/12 rear tires instead of the stock 130/70/12. The reason is to increase the diameter slightly to lower engine speed slightly on my long, fast rides.

The difference is only approximately 2%, but it appears to help a bit in top speed (in perfect conditions) and the reduction in engine speed can't hurt.

The negatives should be a reduction is acceleration but I have not noticed any real difference. This changes much more with changes in roller weights.
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UTC quote
2" in diameter is pretty significant!
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UTC quote
WLeuthold wrote:
On my Vespa GTs, I have been running 140/70/12 rear tires instead of the stock 130/70/12. The reason is to increase the diameter slightly to lower engine speed slightly on my long, fast rides.

The difference is only approximately 2%, but it appears to help a bit in top speed (in perfect conditions) and the reduction in engine speed can't hurt.

The negatives should be a reduction is acceleration but I have not noticed any real difference. This changes much more with changes in roller weights.
My husband runs the same on his GTS and when I ride his scoot, I don't notice any difference.
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jimc
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UTC quote
turboblew wrote:
2" in diameter is pretty significant!
2% != 2"
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UTC quote
turboblew wrote:
2" in diameter is pretty significant!
So you're saying the tire has a diameter of 100" ? I don't think so.
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UTC quote
WEB-Tech wrote:
So you're saying the tire has a diameter of 100" ? I don't think so.
why dont you read the chart above...specifically the diameter of the tire.
@jimc avatar
jimc
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UTC quote
turboblew wrote:
WEB-Tech wrote:
So you're saying the tire has a diameter of 100" ? I don't think so.
why dont you read the chart above...specifically the diameter of the tire.
You replied to Bill (it's assumed you're replying to the post above unless you quote a specific post) - and he wasn't talking about the OP's choice, but his own.
@turboblew avatar
turboblew
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UTC quote
jimc wrote:
You replied to Bill (it's assumed you're replying to the post above unless you quote a specific post) - and he wasn't talking about the OP's choice, but his own.
no I replied to the OP after his post. Had I wanted to reply to specific contributor... I would have done so like this.
@jimc avatar
jimc
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jimc
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UTC quote
turboblew wrote:
jimc wrote:
You replied to Bill (it's assumed you're replying to the post above unless you quote a specific post) - and he wasn't talking about the OP's choice, but his own.
no I replied to the OP after his post. Had I wanted to reply to specific contributor... I would have done so like this.
OK, you do it your way and don't fuss if people get confused - as they will.
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