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Tire Experts Needed - Size Does Matter

  • Thread starter Thread starter Anonymous
  • Start date Start date
A

Anonymous

Guest
Can anyone help me with this tire mystery? I don?t know much about tires so any links to info sites about tire sizes would help too.

First Problem:----------------------------------
My bike : 1982 GS750TZ has specs stating that it comes stock with
Front - 3.5x19
Rear - 4.5x17

When I took a look at the actual rims and tires this is what I found:
Front ?
Rim ? J19xMT1.85
Tire ? Dunlop K391S 100/90x19
Rear ?
Rim ? J17xMT2.50
Tire ? Conti 130/90-17


First off? What the heck? Did some previous owner switch rims on me?
Second? I?d like to get some Dunlop Elites to replace these old sneakers.... what should I be looking for? (riding in rain too)
Third? Any info sites explain what the heck these numbers mean? Can I tell what rim width/diameter fits a tire from the tire size?

Next Problem:------------------------------------------------
My rear tire is not in line with the front. They are parallel aligned but rear is a bit to the right of the front. Like this:

|
This would be inline but:
|


|
This is more like my bike.
|

This rides fine with just me on it. But, what happens with more weight is that the rear wheel comes up and hits against the fender, because it isn?t quite in the center of the fender.

Any suggestions?
 
Right now, you have the same size I do on my bike. But, stock metric tire sizes should be 90/90-19 for the front, and the closest to a 4.5 rear is a 120/70-17 (4.7in.).
I put 100/90 and a 130/70 on mine simply because they were easier to find. It's harder to find the smaller sizes. Last I checked (it's been a few years), Battlax's I THINK were available in those sizes.
Next time I change, I'm going to try harder to find the correct size.

As far as your back tire being offset, check the spacers. Most likely they aren't on the axle in the correct order. Do the sprockets line up, or are they off too?
 
I don't know about the J, made in Japan?

The 19-1.85 are both in inches, diameter and rim width. MT is a tubeless rim, WM is tubetype.

Sizes from inches to metric are given as approximations. Just as well because actual width and height of a series of tires with the exact same designation, even from the same manufacturer, vary significantly.

Stock sizes would be closest to 90/90-19 and 120/90-17. 130 would work on the rear, any larger will reduce your contact patch and adversely affect handling from distortion of the tire on too narrow a rim.

90, 80, or 70 profile won't make a big difference, but will change your final drive ratio as much as a tooth on your front sprocket.

Hope you can find something useful from my rambling.

Guder
 
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