Range of tire sizes?

Hi everyone,
Okay, I'm really confused with all the different letters and numbers they use in tire sizes. I googled and saw the original specs on Wikipedia that told me the factory tire sizes are 325-H19 for the front, and 130/90-H16 for the rear. Then when I googled the one for the front, I found a site that said that tire size was obsolete. I'm sure, that just like cars, the characters represent different things or they use a different system to measure them than they did thirty-whatever years ago. So here's my question: Without educating myself about what the different characters in the new tire sizes mean, can someone help with a range of tire sizes that are used these days that will work on my xj650? Or if you must - can you tell me where I can get educated so I can figure it out myself? (ugh!)
Thanks,
Scott

 

Look for a 100/90-19 for the front and a 130/90-16 for the rear.

 

The 3.25-19 is the inch measurement for the tire. Most modern tires have metric measurements.

This site has quite a bit of information that my help you understand your tires better.

 

There you go.

A 90/90-19 is actually closer to the 3.25, but a 100/90-19 will fit just fine.

And in the rear they already used metric sizing.

A quick explanation of those numbers: The last number (the -19 in front, the -16 in the rear) is the wheel diameter. That's never changed.

What did change is the width measurement, from inches to millimeters; plus they added the aspect ratio ("height" compared to width) like automobile tires have now.

The original 3.25 front meant that it was 3.25 inches wide; the 90 or 100 indicates the width in millimeters. The "/" number (/90 in this case) is the aspect ratio. The old imperial sizing system didn't include aspect ratio.

The "H" is the speed rating, for an H tire it's up to 130mph. A "V" tire is good to 149mph, an "S" tire is only rated for 112mph.

So, a 130/90H-16 is a 130mm wide tire with a 90% aspect ratio, speed-rated to 130mph, for a 16-inch wheel.

 

One (somewhat) impotant note. Don't be tempted to pay for more speed rating than you need. Higher speed rated tires tend to cost more than those that are rated for sane road speeds. A higher speed rating does not equal a better tire, except when discussing the expotentally higher foces that are applied to a tire when ridden at higher speeds.

 

Thanks much guys. I feel like I have all the education I need now.