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Post by sailracer on Jun 22, 2013 14:27:44 GMT -5
Its all good  This is how we learn things, Sharing experiences and tricks and old school vs new school. I'm sorry for hijacking the thread too, but it wasn't a waste. Alot of good info was passed around ;D |
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Post by Paladin on Feb 14, 2014 2:19:56 GMT -5
I was reading on the old forum that a guy went a size or two up, and he gained like 3mph...Has anybody tried this from experience? I don't mind paying extra for larger back tire. My wheels are 13", tire size 130-60-13. Is there a size that could make this possible? I have a Vespa LX150. Stock tire was a Michelin 120/70-10. I got a spare wheel with a Pirelli 120/70-10. Either tire I hit a rev limiter at an indicated 72 to 73 mph. Yesterday I mounted a new tire, a Heidenau K62 130/70-10. Nominal tire size will have 0.2" less clearance on the sides and 0.27" less clearance on top. Close, but did not rub. Nominal 120/70-10 is 16.614" diameter, a 130/70-10 is 17.165" -- 3.3% bigger. Not much, but I don't need much more. Today I was coming home on the freeway and managed to do an indicated 75 mph without hitting the limiter. I figure I was doing an actual 63-64 mph before, and I am now capable to doing an actual 65-66 mph. |
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Post by petrol42 on Feb 17, 2014 1:07:36 GMT -5
To answer the original question which is: "As of now, I going to need to replace my tires soon, my factory tires are 130-60-13, My question is, can I run a 140-60-13 and gain some mph?"
The answer is yes.
In a 130/60-13 tire, the width of the tire is 130mm and the 60 is the sidewall height but it is the percentage of the width of the tire so when you multiply 130 x 0.60, you get 78 mm as the sidewall height.
In a 140/60-13 tire, if you multiply 140 x 0.60, you get an 84mm sidewall height which means a bigger overall diameter tire which in turn will raise your final drive gear ratio and let you go faster.
One warning though is that the tire might be too wide and will rub against the rear shocks so you might want to take some measurements before you commit to buying a bigger tire.
Also, you'll only get a speed increase if your motor still has enough torque to cut through the aerodynamic drag. The only way to know for sure is if you have a tachometer and you could see what RPMs you're at when you reach top speed with your current tire and then you could compare what RPMs you're at with the new tire at top speed. One thing is for sure is that you'll definitely be going faster going downhill with a larger diameter tire.
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Post by rockynv on Feb 20, 2014 0:16:49 GMT -5
On the running a tire reverse of its rotation marks that is usually only done on the back tire of track bikes to offset wear from riding on oval tracks with only left corners or tracks that do not have a equalizing mix of lefts and rights.
Directional tires are designed to sipe water and wear properly with the tire rotating in the direction of rotation indicated by the rotational arrow. When in doubt I call the major tire manufacturers and do not rely on repeated popular misconceptions. The last time I coresponded with Pirelli on this the answer from the tire engineer was do not run a tire front or back on the street opposite the direction indicated by the arrow on the sidewall even if its a rear tire the same size in both positions being used on the front.
If you are considering running opposite the rotational arrow printed on a tire please consult not a well meaning dealer installer who may or may not have the qualifications to answer correctly but the technitions and engineers that work for the tire manufacturer.
If you have room for it you can go up in aspect or width (a wider tire of the same aspect ratio will be taller because its apect or height is a ratio to the width) if you have room for it picking up 5 to 10 mph top end and truing up a speedometer that is off by a few mph with little noticible loss of performance on a 250 but there may be some loss on a 150. If you also are able to move to a Metric Cruiser tire there will less sidewall deflection and potentially greater directional stability. Ride harshness though may be more apparant on bikes that are only about 200 lbs however on 300+ lb scooters the cruiser tires don't present an issue. The cruiser tires will generally last longer due to the deeper initial treads than most scooter tires.
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