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Post by oldchopperguy on Jan 18, 2014 1:37:51 GMT -5
My "new" old Kymco Grand Vista 250 currently has "J" rated (62mph) tires on it; 120/70-12 front, and 140/70-12 rear (correct factory sizes). I regularly find myself FAR exceeding the speed rating just keeping up with traffic and absolutely need to upgrade to better "P" rated (93mph) tires for safety's sake.
Question is this... Has anybody out there in scooter land tried mounting a 130/70-12 tire on the front of their Kymco 250cc Grandvista/Grand Dink? Like most, my speedo reads somewhat "optimistic" showing about 4 or 5 mph fast at an indicated 80. The increased diameter from 120 to 130 would probably bring it close to accurate, not to mention bringing a minor improvement in ride.
I stuck my hand under the front fender, and it looks to me like there would not be enough clearance for the 130/70-12 since the fender is pretty close to the tread already, but I wondered if anyone else had tried the one-size up-size on their Kymco.
Sincerely,
Leo in Texas
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Post by skuttadawg on Jan 18, 2014 1:55:39 GMT -5
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Post by oldchopperguy on Jan 18, 2014 18:09:11 GMT -5
Definitely! That's what I'm doing, but just wondered if the front tire could be up-sized from 120 to 130. I've been reminded to check the Kymco dedicated sites too. Good idea! I really don't think the 130 will go under the fender, but since I'm replacing the tires, it's worth a try. I'm having the dealer I got the scooter from do the tire changes. He will order the tires and change them, and balance the wheels VERY reasonably. He offered to try the 130 but I thought someone might already know if it will work. I don't want to have him go to the trouble of actually mounting and test-fitting the larger tire, (especially since I don't think it will work anyway...) considering he's already been more than generous with me on this sweet old ride. It's VERY special when you find a B&M dealer who will go the extra mile to REALLY serve his customers. Moxie Scooters here in Texas is definitely THAT kind of dealer! They're the BEST! Thanks! Leo |
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Post by scooter12 on Jan 18, 2014 22:34:21 GMT -5
I read up on tires and got a matching pair as suggest( meaning both are Shinko tires). Don't want to miss match tires. The front is a 12 and P rated. The rear is a 10 and a J rate( 62 mph). About the J rated tire- they test them at up to 100 mph.. The recommended speed is always lower than when tested. My concern is the front is a P rated tire( holds 41 lbs of pressure and the rear being a J only holds 32 lbs of pressure. The pressure the front tire held was 32 lbs on Chinese tire. Tread patterns are why they suggest not mismatching tires. My 12 inch tire was only gotten through China and I got the tire purchased new- 4 years old. Tire companies suggest changing after 5 years old. The P rated tire also reads a slight difference in size( old tire was a metric tire size and new size is standard size). I read around on different sites, to findout what standard size fitted the metric size. Honda changed my tires and it fit fine. Saved me about $45 to order this tire in a P rated tire. It is only 6 months old. Shinko is also South Korean tires. So they should be better built tires than a Chinese tire. The major difference in my Chinese 12 compared to a Korean 12 was a 1/4 inch wider tire. That computes to about a 1/8 inch wider on both sides to fit. Had about 1/2 inch on both sides of fender so tire fitted. It is on scooter today..
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Post by oldchopperguy on Jan 19, 2014 1:52:35 GMT -5
Scooter12,
I have noticed a vast difference in width between similar sized tires too. I'm going to go with Shinko tires front and rear, also for compatibility. My old Kymco looks like it's right out of the stone-age of my youth, and is just begging for wide whitewalls. (Not unlike Vespa scoots...) So as long as I'm upgrading to P-rated, I'm using the Shinko whitewall on the front. It comes in 120 and 130-70-12 sizes, but NOBODY makes a whitewall in the 140 diameter for the rear.
So... I'm going to do the rear whitewall with Gledi or Ranger tire paint. You barely see the rear tire, and the fake whitewall will "do". Shinkos are not exactly crotch-rocket caliber, but they ARE P-rated, are nicely made and have a very good rep. They will do me nicely.
I realize the letter-rating is supposed to be "conservative" but before I realized the rating on mine, I ran up to 80mph or so blending onto the freeway. Twice, I felt a shudder as the speed passed on down again below 70mph and I marked the front tire with paint at the rim, like you'd do a variator to check belt position. I then ran back up to WOT at an indicated 84mph (actually about 79mph) and slowed back down. Inspection of the tire showed it had indeed "grown" nearly off the rim, and the shudder was the tire going back down to size. Thankfully, it did not lose air when expanded!
Cheesh! THAT is just a little too close to disaster to suit this old codger... I've SEEN what happens with a catastrophic tire/wheel failure on a motorcycle at highway speeds... It ain't pretty...
My dealer says he's never had any problems with Shinko tires, and recommends them as a good value for the money. The only trouble he's seen is with low-end Chinese tires, run over their recommended speeds. And those Shinko wide-whites are SO pretty! LOL!
Thanks for the advice,
Leo in Texas
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Post by scooter12 on Jan 19, 2014 13:24:32 GMT -5
The front was a 4.00 12 Chinese tire originally and the tire I got on front now is 110/  12( it means tire is 4.25 width, means sidewall is % of width( so about 4.00, 12 is rim size. It is the closest size tire to 4.00 12. The only thing that bothers me is the max pressure being more than rear tire. But it should hold still if air pressure is around 39 lbs.. Remember max air pressure just means simply don't put more than 41 lbs in the tire. Less air pressure is ok. Just not to low that the scooter rides running. Tire mismatching also means don't put a nobby tire on front and a street tire on rear. On my scooter, it originally came with tire street tires on it. The first time I ordered a front tire, well it was dual street and trail. I was not happy. The Shinko tire is strickly street now. So it matches the rear tire. Gives better traction and handles corners better. |
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Post by scooter12 on Jan 19, 2014 14:04:36 GMT -5
5 1/8 inches wide is 130mm.. Is there clearance under front fender? There would not be clearance under my Bali 250.. Probably best bet is to measure fender and see if it has enough clearance with measuring tape.. My scooter had about a 1/2 inch more than tire needed. You don't want to get so close that a rock would be picked up off street from 130mm tire and compromise between tire and fender. Fender would crack.. This was my concern too.
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Post by shalomdawg on Jan 19, 2014 16:20:24 GMT -5
howdy, i'll respond somewhat from ignorance perhaps.
the pressure reading off the tires I have seen are not maximum pressure the tire is able to contain rather it is the pressure at which the tire caries it max LOAD. at less than max load one may be able to use more pressure than that but not much. something less than 5 lb more should be ok? just a useless brain fart probably.
lotsa miles and smiles to ya
ken
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Post by rockynv on Jan 20, 2014 7:41:35 GMT -5
P-Metric tire sizes are width/profile(percentage to width) and rim size. You may get a taller 120/80 in there but wider up front can be difficult if the forks are not spaced far enough apart. Yes wider due to profile being a percentage of width will also increase diameter. Also you have to consider that the front rim may already be at its max acceptible tire width with the 120 on it and may pinch the bead of a wider tire too much stressing the rim and impacting the balance and stability of the bike while cornering. A taller front tire can also introduce headshake unless a taller rear tire is also used. It is a balancing act.
Here a dealer, bike or tire, can loose their license if caught putting tires with too low a speed rating on a vehicle. Someone cheated with the speed ratings of the tires on your bike and it is in your best interests to correct that situation.
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Post by oldchopperguy on Jan 20, 2014 21:02:00 GMT -5
P-Metric tire sizes are width/profile(percentage to width) and rim size. You may get a taller 120/80 in there but wider up front can be difficult if the forks are not spaced far enough apart. Yes wider due to profile being a percentage of width will also increase diameter. Also you have to consider that the front rim may already be at its max acceptible tire width with the 120 on it and may pinch the bead of a wider tire too much stressing the rim and impacting the balance and stability of the bike while cornering. A taller front tire can also introduce headshake unless a taller rear tire is also used. It is a balancing act. Here a dealer, bike or tire, can loose their license if caught putting tires with too low a speed rating on a vehicle. Someone cheated with the speed ratings of the tires on your bike and it is in your best interests to correct that situation.
Good advice...
I have about made up my mind to go with the factory-size tires (120/70-12 front, and 140/70-12 rear). They ride just fine, but I do need to upgrade to "P"-speed rating. The dealer did put the current tires on new before placing the scoot on the lot (along with new belt, muffler and brakes, oil-change, tune-up and detailing). He truly did his part, and then some. The '07 Grandvista indeed came from the factory with "J"-speed rated tires, and these are direct replacements. The thinking was that anything over 60mph was fully adequate... WRONG!
The scooter is capable of 80mph+ and it needs "P"-rated tires in my book. Just me, but... I want a "safety margin" rating 12mph FASTER than top-speed. Not a "danger margin" rating 20mph SLOWER than the bike's top speed... LOL!
Now that I'm highly interested in the speed ratings of scooter tires, I'm amazed at the local Vespa, Kymco, Sym, and Japanese scooters (all capable of 80mph+) I see, wearing J-rated tires. I've asked riders about that, and they most all say "It's OK, I never go faster than 60..."
Cheesh, how do you not exceed 60 during a "kamikaze" entrance-ramp sprint into a "hole" in the 70 to 90mph traffic, before working your way into a lane running 65-70 to cruise in?
Seems to me that a whole lot of riders pay MAJOR attention to wearing high-end, high-tech helmets, jackets, "body-armor", boots, gloves, etc. and then risk performing a dozen or so somersaults down the tarmac when their sub-standard tires go south... And highly-suspicious "tire activities" during even short bursts to 80 and back down have convinced me that any prolonged running over rated speed WILL eventually cause the tire to leave the rim. Yup... Off comes the baloney, down goes the rider... Yup. Seen it happen on a crotch-rocket, DO NOT want to experience it... No sir... Do NOT want to experience THAT stunt.
I never thought about it with my old Chinese 150 since it would NOT go faster than 58 mph. On that scooter, J-rated tires were just fine. In fact, the factory Kendas handled exceptionally well. But with a highway-capable ride, one really should have highway-capable tires... I think... LOL!
Whatever tires you ride on, RIDE SAFE!
Leo in Texas
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Post by SylvreKat on Jan 20, 2014 23:16:55 GMT -5
Leo, you make me wonder what tires my Italian Stallion has on him. Not that I need to worry about going over 60 period. Or really, over 50. Maybe I'll remember tom and I'll check what they say. Then again, I may not. I'll be going to sleep here soon, and memory faileth after a good snooze.  Cheesh, how do you not exceed 60 during a "kamikaze" entrance-ramp sprint into a "hole" in the 70 to 90mph traffic, before working your way into a lane running 65-70 to cruise in? And thus you have one BIG reason I'm unlikely to ever try daring the highway. >'Kat |
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Post by oldchopperguy on Jan 21, 2014 1:59:23 GMT -5
Leo, you make me wonder what tires my Italian Stallion has on him. Not that I need to worry about going over 60 period. Or really, over 50. Maybe I'll remember tom and I'll check what they say. Then again, I may not. I'll be going to sleep here soon, and memory faileth after a good snooze. Cheesh, how do you not exceed 60 during a "kamikaze" entrance-ramp sprint into a "hole" in the 70 to 90mph traffic, before working your way into a lane running 65-70 to cruise in? And thus you have one BIG reason I'm unlikely to ever try daring the highway. >'Kat
I live right at the north end of the D/FW Int'l. Airport, and to go most ANYWHERE outside of my own little town of Grapevine, and with recent changes to the roads, you almost MUST hop onto the freeway. Almost all the local 4-lane surface streets now have entrances and exits that put you on the limited-access. (Some leave you no choice...). These WERE the sleepy home-town roads I rode to and from most places I needed to go a couple of years ago. The speed-limits were mostly 35 to 45mph. Traffic ran 45 to 65mph, and the little 150 would run nearly 60 WOT which was JUST BARELY enough to get by. Now, the traffic is just TOO aggressive to handle it with a 150. That's why I sought-out the old 250 I now ride. It's not a super-long touring scoot, and still handles like the little 150 in slow, tight traffic, but... It will accelerate with most average cars (actually, it's pretty frisky!) and roar up even steep entrance-ramps at 75 mph or better. Once on the level, it will move on up to around on the speedo, (actual speed about  -85mph). That's WOT, and, JUST barely enough to sneak into a "hole" in traffic and maintain that speed long enough to find a lane where I can cruise 65 to 70mph to my destination. Little "Minnie Mouse" will cruise 70 as smooth and stable as my old Harley Electra-Glide. AMAZING! But it's NOT safe to do that on J-rated Kendas... I would think your Piaggio would do highway speeds OK, and be comfortable. You may want to check your tires' speed rating. J is good for 62mph, P is good for 92mph. There are many other ratings in between, and FAR above, but the 92mph P's should be good for any scoot up to a mild 250. I think the newer 300's and larger, with fuel-injection however will exceed 100mph and should have very high-speed tires for safety. High-performance tires only cost a little more than the lower-speed tires and are a good investment in safety. I truly enjoy the ride on the freeway. It's amazing how quickly you get used to it, so long as the scoot will run fast enough. But I DO want to know that my tires are up to it... LOL!Ride safe! Leo |
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Post by SylvreKat on Jan 21, 2014 19:50:06 GMT -5
Well, I looked tonight. But I'm not sure where I'm looking. After all the size info is "M / ##P" So, are they Ms or Ps?
It also states it's the front tire. I suppose that's good to know, in case I get turned around on my bike, ha. I made a funny!
>'Kat
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Post by Jarlaxle on Jan 22, 2014 11:05:02 GMT -5
The speed rating is a letter after the load index. Example: OE rear tire on a Helix is a 120/ -10 66J. That one is J-rated. The snows on my Dakota are 215/75R15 99S. They are S-rated (112MPH). Best guess: yours are J-rated. Having said that...at 70MPH, I'd trust a J-rated tire from a reputable company (Bridgestone, Michelin, Dunlop) more than an S-rated tire from some "China Star Rubber Company"! |
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Post by keltex78 on Jan 23, 2014 20:10:29 GMT -5
Odd about speed ratings, I bought Shinko SR429s for my 250 and they were advertised as J-rated for 62mph on one site but L-rated (75mph) on another. Fortunately, they actually were 75mph rated which is over the limit on the roads I ride on so well suited for me. I stay off the Interstate entirely and stick to lower speeds anyway as much as possible. My factory tires were K-rated (68mph) so probably border-line unsuitable for me...
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12( it means tire is 4.25 width, 
-85mph). That's WOT, and, JUST barely enough to sneak into a "hole" in traffic and maintain that speed long enough to find a lane where I can cruise 65 to 70mph to my destination. Little "Minnie Mouse" will cruise 70 as smooth and stable as my old Harley Electra-Glide. AMAZING!
