[AFNurse]

Now here is a dumb question, but it is one that I don't know the answer to... my bike has the MT90B16 72H front tire, and the MU85B16 77H on the rear....now if I was going to look for a tire NOT made by dunlop, what is the actual tire size (sizes kinda like the stuff you see on cars and such). Also, what would be approximatly the biggest tire that I could put on the factory rims with absolutly NO mods made to the bike other then a tire change? I am riding a 2004 E Glide Standard. I don't need new skins yet, but at some time I will and would like to know what to look for, or begin looking for, so when the time comes, I can run right out and get what I need/want!!! Thanks for the input!!!

[Murphdog]

The equivalent of a MT90B16 is a 130/90-16, an MU85B16 is a 140/90-16.
Here's a link to Metzler's brochure.
http://www.us.metzelermoto.com/media/vtwin_04.pdf

[Seahag]

Originally Posted by Murphdog

The equivalent of a MT90B16 is a 130/90-16, an MU85B16 is a 140/90-16.
Here's a link to Metzler's brochure.
http://www.us.metzelermoto.com/media/vtwin_04.pdf

The only problem with the 140/90/16 is you have a slightly higher sidewall profile than with the MU85B16...which would actually be equivalent to a 140/85/16...the wider your tire on the stock rim width...the higher it will push your sidewall height too.

I never noticed a negative impact the past three years when I ran the MU90B16 in the Dunlop Elite II touring line...but this year I went up to a 150/80/16 and when I placed the wheels (front and rear) side by side you could see the rear was about 3/8" higher than the front wheel...kinda offseting the effect of my lowering kit...but not by much.

I went to the 150 figuring to have a slightly bigger contact patch for more traction and possibly better tire life. I've heard not to try running anything wider than a 150mm tire on the stock rims or the bead may let go.

[bxbutch]

how does that 150 work out as far as clearances & speedo readings

[Seahag]

Originally Posted by bxbutch

how does that 150 work out as far as clearances & speedo readings

I had to shim the rear drive pulley over about one eighth inch...which I did with a kit I bought online last year. I cut and pasted the entire instructions on this site at the time...so you can do a search if you need more info on that. Other than that, it fits fine.

The speedo on modern harleys is run off a sensor on your transmission...so tire size doesn't affect speed readings at all.

[rose_guy]

Originally Posted by Seahag

The speedo on modern harleys is run off a sensor on your transmission...so tire size doesn't affect speed readings at all.

Huh??? This doesn't make sense to me. It seems to me a transmission rendering of the speed would be effected by a tire change. Could someone explain how it is not.

[Seahag]

Originally Posted by rose_guy

Huh??? This doesn't make sense to me. It seems to me a transmission rendering of the speed would be effected by a tire change. Could someone explain how it is not.

The ecm or some other control module on your motorcycle is programmed with the gear ratios that came stock with your harley. For any given engine rpm there will be a corresponding speed produced with a given set of gear ratios...this is why when you buy a six speed or start changing gear ratios you need to also get your ecm/computer recalibrated. Changing tire diameter has no effect on the speed of the spinning transmission....a bigger or smaller tire will simply have more or less revolutions comparitively to stock...but the distance cover per measure of time remains the same. When the speedos were attached to the front hub, tire variations could cause the speedo to error...with a lower sidewall height and overall smaller circumfrence, the wheel would complete its revolutions faster and thus the hub mounted speedo would think you were going faster...and conversely, a larger diameter/higher sidewall tire would take longer to rotate completely making the speedo read slower than actual.

There is a magnetic pickup on top of the twin cam tranny on the right hand side (atleast on the touring models)...in the vicinity of the oil fill spout. By the way, if your speedo starts acting up, pull the sensor out and clean the metal filings off and see if it will return to order....its worked for me and a couple other people I know....beats buying a new speedo sensor.

[rose_guy]

Originally Posted by Seahag

a bigger or smaller tire will simply have more or less revolutions comparitively to stock...

Again, I am confused. Are you telling me by changing tire diameter the tire will change RPM of the wheel? A smaller tire will take more revolutions to cover the same distance. So wont that change the speedo readings? It still seems to me if the transmission and drive gears remain unchanged the speedometer reading is off if you change rear tire diameter. Follow my example here. Assume a 1 to 1 gear ratio from the transmissiion to the wheel. That means for every revolution of the output shaft of the transmission you get one full revolution of the rear wheel. If you have a 10 inch wheel every rev of the transmission travels the motorcycle 10 x 3.14 or 31.4 inches. change that to a 20 inch wheel and you have 1 rev moving the bike 20 x 3.14 or 62.8 in. It seems to me there is no difference between an tranny output shaft type of speedometer take off and a rear wheel hub take off the ratio is fixed between the two. Now, if you mean that changing the front tire has no effect on the speedometer reading I agree totally. The front wheel change would effect speedometers that have a front wheel pickup.

[hotroadking]

If you change the outside diameter of the tire then you'd change the actual speed of the vehicle. The speedo would be off.

[Seahag]

I guess that would make sense...but then I don't know why they changed to the transmission pickup type speed sensor ...now having said that it would make sense...it must be so minute in most cases as to make no discernable difference in final speed. My route to work takes me on some fairly well traveled roads where they often place those radar "check your speed" boxes....and my speedo has always checked out just fine....even with going to the 150 tire this year which was admittedly a little taller than stock.