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Discussion Starter · #1 ·
Pardon me if this is something that should be expected, but I found this odd enough to question...

I purchased a set of Michelin Pilot Power Pure SC tires ahead of time, and had them installed by my dealer, before I even took delivery of my Grom, last Friday. When they brought out the Vee tires to me, to stick in my car, I was surprised at how much wider they were than the Michelins - to the point, where I thought they'd brought me someone else's tires. I verified that both sets are in the correct size (120/70-12 front and 130/70-12 rear), but taking a ruler to them, verified that the Vee's are half an inch wider than the Michelins.

I thought the first number on a tire size is the width, in millimeters, and the second was the sidewall height, as a ratio to the width. If that's the case, then how can two tires with the same 120 (or 130) width designation, be off by half an inch from each other?

Has anyone else with the Michelins noticed this difference?
 

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Michelin's moto tires run small. Always have. I run Michelin S12's / M12's on my offroad bikes, and always order a size up than what I would normally for another brand. I thought that might be the case for the Pilot Powers as well and was waiting for reports here. Sorry you had to be the one. :apologetic:

Both front and back smaller eh?
 

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Pardon me if this is something that should be expected, but I found this odd enough to question...

I purchased a set of Michelin Pilot Power Pure SC tires ahead of time, and had them installed by my dealer, before I even took delivery of my Grom, last Friday. When they brought out the Vee tires to me, to stick in my car, I was surprised at how much wider they were than the Michelins - to the point, where I thought they'd brought me someone else's tires. I verified that both sets are in the correct size (120/70-12 front and 130/70-12 rear), but taking a ruler to them, verified that the Vee's are half an inch wider than the Michelins.

I thought the first number on a tire size is the width, in millimeters, and the second was the sidewall height, as a ratio to the width. If that's the case, then how can two tires with the same 120 (or 130) width designation, be off by half an inch from each other?

Has anyone else with the Michelins noticed this difference?
I will have to check when I get home. I have a pair still sitting in my truck and I will see if I get the same thing. You are correct on how tires are measured.
 

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Discussion Starter · #5 · (Edited)
Michelin's moto tires run small. Always have. I run Michelin S12's / M12's on my offroad bikes, and always order a size up than what I would normally for another brand. I thought that might be the case for the Pilot Powers as well and was waiting for reports here. Sorry you had to be the one. :apologetic:

Both front and back smaller eh?
Yeah, both back and front are smaller.
 

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Discussion Starter · #6 · (Edited)
I just went outside and measured the tires.

Front tire width: 5" Vee, 4.25" Michelin (120mm = 4.72")
Rear tire width: 5.5" Vee, 5" Michelin (130mm = 5.12")

Granted, the Michelins are mounted to the rims and the Vees are not, but side by side, there is a huge difference, for such a small tire.
 

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Pardon me if this is something that should be expected, but I found this odd enough to question...

I purchased a set of Michelin Pilot Power Pure SC tires ahead of time, and had them installed by my dealer, before I even took delivery of my Grom, last Friday. When they brought out the Vee tires to me, to stick in my car, I was surprised at how much wider they were than the Michelins - to the point, where I thought they'd brought me someone else's tires. I verified that both sets are in the correct size (120/70-12 front and 130/70-12 rear), but taking a ruler to them, verified that the Vee's are half an inch wider than the Michelins.

I thought the first number on a tire size is the width, in millimeters, and the second was the sidewall height, as a ratio to the width. If that's the case, then how can two tires with the same 120 (or 130) width designation, be off by half an inch from each other?

Has anyone else with the Michelins noticed this difference?
Can you take a pic of both tires side by side, so we can see the difference in widths? thanks!
 

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Discussion Starter · #11 ·
Can you take a pic of both tires side by side, so we can see the difference in widths? thanks!
My phone takes horrible photos, but here's the best picture I could get, of the front, tread to tread:
Tire Automotive tire Wheel Wire Auto part


I tried taking a picture of the back tires, but because of the whale tail fender, I can't get a good photo of them, together.
 

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Thanks...yeah they are wider....I like the chain lock you're using..what brand, where did you get it and the price?
 

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Discussion Starter · #13 ·
Thanks...yeah they are wider....I like the chain lock you're using..what brand, where did you get it and the price?
That's a Kryptonite New York Fahgettaboudit chain with disc lock. It comes in 3.3' and 5' lengths, and runs between $123 to $157, depending on which one you get. I bought it from Motorcycle Superstore.
 
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The other thing going on here is you are comparing a tire that has been on the bike and one that hasn't. Tires expand. Just taking a tire and placing it in the sun makes it significantly larger. In fact, if you mount your own tires, you learn quickly to let the new tire bask in the sun before trying to mount it.
 

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I guess the only way you can really tell the difference, would be to find another Grom with stock tires and compare them side by side.
 

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Michelin moto tire sizes run small in the same indicated "size".

Sizing up in the back to a 140 is fine, but they don't make a larger front. I'm now looking elsewhere - to Heidenau or Pirelli most likely.
 

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Here is what I was talking about. Note the huge difference in the new and old tire size before it is mounted that is....go to 4:50 and see the difference between a tire that has been mounted and one that hasn't.
 

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I know those Vee rubber tires run large in 10" sizes, if you've ever ran a 10x8 with a 130/90 you'll understand how drastic tire sizes can change between brands, these Vee tires (idk the model) are on par size wise with Pirelli SL26 which in 10" sizes run much larger than most tire brands

also when comparing you have to use two new unmounted tires or two new tires mounted.. Age and tire pressure make a pretty big difference when comparing new and unmounted to old and mounted

I'd like to see a 140 SC mounted next to another grom with the oe Vee mounted
 

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If you are after top end, a lighter, thinner, harder rubber tire with more air pressure would improve your top speed. I normally increase all my tire pressures by a couple of psi. Running the Grom at 31psi shouldn't hurt anything and if the Pure is indeed thinner, that is probably a plus for top end. It is normally recommended in large part because of the light weight. It's what I'll be using. Many Vespa owners use the Pure on the front.
 
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