I've done the 130/70 and the 130/90 and all I noticed is that the tire is taller. Luckily I have 2 rear rims and have one of each mounted. Honestly I like the stock 130/70 better in appearance and handling. Lots of people put the Katana tire on the rear and its a 150/70 (correct me if I'm wrong here). And I like the Bridgestones. But the pirelli is a nice tire as well. Odds are you'll like the pirelli in the stock size over the stock anyway.

Fact of the matter is these GS500's are a great bike and anything you do is really an adjustment for the rider and not the bike. That's why there was such a long run in these bikes with very few changes other than cosmetic.

Another tire you might have looked at is the Avon Roadrider. I've been using them for a while now, along with other brands also of course.
Tony

Quote from: Cal Price on January 06, 2011, 07:12:01 AM
I asked this question on here years ago without any credible answer.
Does fitting a bigger tyre have any measurable engineering advantage?
I am far from convinced that it has none but I'm willing to be converted. "Looks cool" won't do it for me, I'm looking for a performance or economic advantage.

We've used a lot of tires since you first asked Cal and I'll say there is very little performance advantage sizewise but I can argue some economic advantage, bigger tires last longer.  My last tire before my present 150/70 Roadrider was a 140/70 Roadrider that went about 15k miles for me and I have about 16k miles on the 150 now with 2 mm tread left so it looks like it will go close to 20k miles before I hit the markers.  I've used 3 different front and 6 different rear sizes on my GS's over the past 12 years and 160k GS500 miles. 

http://img.photobucket.com/albums/v443/jcp8832/GS500tirelogs.jpg

It's definetly different strokes for different folks when it comes to tire milage Cal, I can remember when I had a rear BT45 more than half worn out at 2k miles and changed over to the Z4/Z2 radial combo before heading for the mountains to play back in 02.  Now I'm riding more like a little old man should ride so the milage is much better.   I've traded in fast for cool I guess. 

Thank Jack - always good to hear from a true guru. I might give a larger tyre a try next time as i seem to need a set every year which I don't think is very good, I reach state pension age in a month but I'm trying to ignore it, however with the price of fuel here i will be moderating my riding and driving style along with a lot of other people!

Thanks  GSJack i had a similar experience with the BT45's
The first one, that came fitted to my bike i got about 18,000 km out of..
after that i got another BT45 fitted, and decided that i could step up my ridding a bit, as the bike was run in..
It lasted me 500km, i had worn the sides out, and there was a big strip left up the center and a noticeable ridge where the 2 compounds of the tyre met..
The bike shop replaced this tyre free of charge with a dunlop, as they had never seen this done to a tyre on a gs500 or similar bike..
The dunlop arrowmax only lasted about 7000km..
so now im onto the pirelli's....

Quote from: luohanfan on January 06, 2011, 04:12:02 PM
Thanks  GSJack i had a similar experience with the BT45's
The first one, that came fitted to my bike i got about 18,000 km out of..
after that i got another BT45 fitted, and decided that i could step up my ridding a bit, as the bike was run in..
It lasted me 500km, i had worn the sides out, and there was a big strip left up the center and a noticeable ridge where the 2 compounds of the tyre met..
The bike shop replaced this tyre free of charge with a dunlop, as they had never seen this done to a tyre on a gs500 or similar bike..
The dunlop arrowmax only lasted about 7000km..
so now im onto the pirelli's....

Got 23,000 out of my first BT45 rear. Currently have 13,000 on the Sport Demon and all is good. *I* perceived better handling on them - real or in the head, it's how *I* perceived them.

Michael

Quote from: Cal Price on January 06, 2011, 07:12:01 AM
I asked this question on here years ago without any credible answer.
Does fitting a bigger tyre have any measurable engineering advantage?

More effort to turn in is all that I noticed. When I went back to a 130 right before I sold mine, I was amazed at the difference, and reminded of why the Gs is such a great bike.

Quote from: luohanfan on January 05, 2011, 09:38:14 PM

Quote from: trumpetguy on January 05, 2011, 07:00:55 PM

Quote from: luohanfan on January 05, 2011, 02:38:20 AM
It must be too powerful for my newb computer skills, because i didnt find the info i was after, i must have used the wrong "keywords"
anyway, thanks for the advice i will look again.

Plug in these words in the Search box:  tires BT45 Sport Demon

Lots of information.

Sorry if was too grumpy.  BTW, there is quite a bit of information here on motor oils, too.   

Hmm, maybe im doing something wrong.. results for bt45 are... this thread..
results for sport demon are....this thread 

I think i better leave the oils for a later date, this could be a big learning curve lol..

Copy and paste the three words (plural -- i.e. all three) into the search dialog.  I get something like 25 hits, most with some kind of comparison.