Oh n o not another Tire thread!!!! YES but this one isnt to say Yours Sucksnand Mine rules (well that is true if you still run Dunlops, but thats another story) ANYWAYS!!! I have fallen in LOVE with the Avon tire, cannot help it, bikes NEVER handled better. SO with that said I switched from the Metzler 200/50/18 rear tire to the Avon 200/55/18 tire 3 months ago, Now its a Bit taller so I always wondered the Difference.
Well now 2 different times I have riden with people with OEM sized tires on their bikes.
first time was a Leg of our ride to Pismo Beach for our annula SoCal NorCal get together, Me on my Vrod Jon on His Night Rod, We both filled up at the same place and rode the same roads the same way, when we stopped again, my ODO said 100.00 miles, His read around 110. So that was the 1st test.

Today Pascal and I road up to Wrightwood CA, Lovely ride. Anyways we filled up etc... all the same, I pulled over at Exactley 10 miles to take a pict, I asked him what His ODO said and it was 10.5 miles. So the conclusion is that the Avon 200/55/18 puts .5 miles LESS on your bike for every 10 miles you ride.
Bow the question IS, does my MPH also change? Does this now effect my MPG as I usually fill up at 85-90 miles to be safe, that is Now actually over 100 miles with the old tire size.

10% in mpg is hard to believe from a tire swap, you can have differences in engine requirements and/or riding habits, set-up ect, that are skewing the results. Even tire pressure, weight of riders, type of tires, miles on the motor and so on will contribute. You are also coming off a worn set of tires as a comparison.
But yes, your MPH can change as well, however, it is my understanding that the V-Rod's internal computer will compensate for very mild changes such as this is.

* I too have been a huge fan of Avon tires, the new Cobra's are by far the best bang for the buck and great looking IMHO.
Metzler - great tire, does not out perform the Avon (Cobra) by much, if any and the lack of any real tread life got annoying to keep buying. I'm waiting for Perelli to do a 240.

 

No I am not stating I am Getting 10% MPG, I am stating MY ODO states that I am going .5 miles LESS every 10 miles than the same bike traveling the same distance is with the OEM tire size. What I am Going to Assume though is that since I fill up around 90 miles I should start doing so when the ODO says 80 .

 

I just quickly measured my 180 radius, currently 33cm. If it had another 1cm radius it would roll 213cm per rev as opposed to 207cm per rev. So, !cm extra in radius gives an extra 6cm roll per turn of the tyre. Do this with yours and your mates tyres and work out the extra circumference as a percentage, then compare it with your mileometer differences or speedo differences

using 2 times 3.142 times radius. (how do you do the multiply sign on a keyboard)

 

(how do you do the multiply sign on a keyboard)

X

 

Bow the question IS, does my MPH also change? Does this now effect my MPG as I usually fill up at 85-90 miles to be safe, that is Now actually over 100 miles with the old tire size.

Yes you MPH does change and you may need to adjust your mileage for fill ups. If you speedo says 55, with the 200 Avon you are actaully going 58.5
Here is a Calculator to get your tire diameter
http://4lo.com/calc/gearmetric.htm
Here is a calculator to show how your speedo will be off with different tire sizes
http://4lo.com/calc/gearspeedo.htm

 

well if your showing less miles your odometer you should show less mph when riding as well.....question is by how much is the odometer/speedo out? one easy way to check is go 60 mph and check your navigation device and see what it's showing for speed....imo your speedo should be slower then your actually going according to your above posts? again this could be from a few different things but chances are it is because of the Avon being slightly higher which in theory makes you show slower speed and mileage..... so in essence when when do 90 miles you may have actually ridden 95 or there abouts??? check you speed with a navigation device and go from there.

 

Did you notice the bike needed less countersteer.... and was easier to stand up at the end of a curve? I've eyeball the two side by side and have noticed the cobra has more of a rounded profile, while the metz has a flat patch..... I'm guessing this is the key...

 

Yes I have and hitting the canyons is so much easier now (well will be even more when my New Front arrives, Back ordered 4 weeks now) My Tech told me He TRIES to explain the difference between the 2, being that Metz have this Flat Patch but most people dont do it because Avons are usually $30-$40 more.

 

If you have a gps, check your MPH with that. I checked mine before and after installing the Avon's and yes it was 2 to 3 MPH different, depending on your speed. Love the Avons.

 

It's a proportion.

Size 50 is to 100 miles as size 55 is to X.....X=110miles.

The odometer/speedo needs to be re-calibrated using some voodoo & angel dust.

I noticed the exact scenario with my tire change.

 

Heh...
Ok Myths and assumptions aside...
The avon is a larger tire profile, this means that it travels MORE distance with each rotation of the tire. This will affect your speedometer. The difference is right at 11%. Meaning that if you're doing 60mph on your speedo, you will be doing closer to 66.6mph. If you were used to filling at 90 miles, filling at 80 is a good bet. There are devices that will allow you to change your speedometer's calibration. I have verified that doing 80mph on my speedometer puts me just shy of 90mph on a radar gun. A quick fix for this, to get it closer to actual mileage and mph, Lux, i don't know if you ever did the conversion to the 28 tooth front pully, but if you did and you had your ECM flashed for it, you can get it flashed back to the 30 tooth despite having the 28 tooth and your speedo will be closer to accruate.

 

Alright then what about divide, cant see it on mine.
By the way(can of worms), i always top up at 125 ish on my small tank ,last week i did 135

 

You're joking?

"/" works pretty good on my keyboard, hehe.

 

I remember seeing somebody do something on their keyboard which got it into calculator mode,would that be a 'special' keyboard. i dont work in I.T. so am not a pc boffin

 

On my fancy calculators, / is divide and * is multiply.

I honestly havn't calculated mileage on my 03 in a couple of years because the fuel gauge works.Just after the light comes on I put in an average of 2.8 U S gallons,which is an average of 100 miles.

I can say I got caught speeding on the 03 w a 240-50 metz on the rear.My speedo showed 69 mph,yet the cop said she clocked me @ 67 mph.