Max Rear Tire Width

[adidascanada]

What is maximum width of a rear tire that can be install on a standard GS500F?
I need a new tire and would like a wider one. I notice that the limiting "factors" are the rear brake "arm" and the chain cover. Thanks

[Alphamazing]

140

The limiting factor is the wheel size.

[drincruz]

http://wiki.gstwins.com/index.php?n=Upgrades.RearWheel

biggest possible i'd say is a 160. but that assumes the 4.5" wheel swap. then again, you can also look into a new swingarm, but that's even more work.

g'luck.

cheers,
~drin

[gsJack]

I consider 150 to be the max practical tire width for the GS500 on a oem 3.5" wide wheel.  It will clear the chain guard but will come close to the brake torque link and might touch it depending on brand of tire, they all vary a bit in actual measured width.  Easy to bend the brake link to clear all 150 tires.

Traditionally both the the 150/70 and 140/70 tires have been made for a 4.0" preferred rim width.  They have generally been approved for fitment on 3.5-4.5" rims for bias tires and for fitment on 4.0-4.5" rims for radial tires with some tire makers approving them for the same 3.5-4.5" range as bias tires.

More recently the 140/70 Pirelli Demon and Avon Roadriders have been sized for 3.75" rims making them an equally good fit on either 3.5 or 4.0" rims.  The 140/70 Michelin Pilot Activs have a 3.5" preferred rim width.

I've run 130/70, 130/80, 130/90, 140/70, 140/80, and 150/70 rear tires on my GSs, the 150/70 in both bias and radials.  Only mod to accomodate these was putting a little bend in the brake torque link.

Anything wider than a 150 needs a wider wheel.  The 160 comes close or actually touches the chain on a wider wheel depending on tire brand.

[Alphamazing]

Traditionally both the the 150/70 and 140/70 tires have been made for a 4.0" preferred rim width.  They have generally been approved for fitment on 3.5-4.5" rims for bias tires and for fitment on 4.0-4.5" rims for radial tires with some tire makers approving them for the same 3.5-4.5" range as bias tires.

Today, as I know you've seen, very few 150 series tires are recommended for 3.5" rims. In fact, most are recommended for 4.0" and 4.5" rims. This is assuming sport tires. I believe the ones that you found were Continentals, and even then it was fairly close.

And for that matter, even with a wider wheel, some 160 section tires will still contact the brake torque arm, and other various parts. Case in point --> http://gstwins.com/gsboard/index.php?topic=27304.0

The Katana wheel swap is the most efficient way of getting proper wheel size for a variety of larger width sport and sport-touring rubber.

[gsJack]

Both the bias and the radial sport touring tires come in a 150/70 size and I'd use any of them on my 3.5" rear rim.  All of the 150/70 bias and half of the 150/70 radial tires are approved for fitment on a 3.5" rims by their makers.

The sport/supersport type radials come in a 150/60 size and none are approved by their makers for fitment on a 3.5" wheel in this country and I wouldn't use them anyway but many do particularly on the Ninja 500 which has the same size 3.5x17 rear rim as we do.  The 150/70 size won't fit the Ninja 500 so those wanting radials are forced to use the smaller diameter 150/60 sport radials.

I previously used a bias 150/70 Lasertec and a radial 150/70 RoadAttack and am currently using a bias 150/70 Roadrider all of which were approved fitments by their makers.

[NF11624]

I just put a 150/70 Avon Roadrider on my GS last month.  I took the brake torque rod off and hammered on it in the driveway for a few minutes to bend it because I was worried about it touching.  Just look at the manufacturers websites to find the recommended fitments (be prepared for a bit of searching on some of them though).

I know that this is a peripheral issue - but keep in mind the profile of the tire that you want to switch to.  A 150/70 tire has 11mm more something (either radius or diameter... not quite sure) than the stock 130/70.  This will change the steering a little bit - but also acts as a sort of change of gearing due to circumference of the tire.  I've found that with a 150/70 tire my rpms are about 300 lower than with stock (for example:  On a 130/70 at 50 mph indicated in 5th gear - 4500 rpms.  On a 150/70 at 50 mph - 4200 rpms).  I Don't think many people take this into consideration, but its an interesting side effect that you might want to think about.

Good luck on your tire search!

[Alphamazing]

I just put a 150/70 Avon Roadrider on my GS last month.  I took the brake torque rod off and hammered on it in the driveway for a few minutes to bend it because I was worried about it touching.  Just look at the manufacturers websites to find the recommended fitments (be prepared for a bit of searching on some of them though).

See, with all that effort, it'd be easier to put forth the same effort while at the same time swapping out the rear wheel for a Katana 4.5"er and getting a wider wheel to fit proper sport rubber, if that's what you're going for. The Katana wheel swap is trivial.

[adidascanada]

Thanks everyone!
I'd prefer to stay away from wheel swaps and modifications to the brake torque arm.

BTW A modified brake torque arm to make room for a larger tire/wheel does't look like it would be too hard to fabricate, has anyone actually had one made? Can these be purchased and where?

Thanks Again! 

[qwertydude]

Modyfying the brake torque arm is easy, you just hammer it down some to bend it away from the edge of the tire.

[NF11624]

I just put a 150/70 Avon Roadrider on my GS last month.  I took the brake torque rod off and hammered on it in the driveway for a few minutes to bend it because I was worried about it touching.  Just look at the manufacturers websites to find the recommended fitments (be prepared for a bit of searching on some of them though).

See, with all that effort, it'd be easier to put forth the same effort while at the same time swapping out the rear wheel for a Katana 4.5"er and getting a wider wheel to fit proper sport rubber, if that's what you're going for. The Katana wheel swap is trivial.

Thing there is the $$.  I wanted higher quality rubber and wanted to get a little bit wider, but didn't want to add the cost of a new wheel on to that.  I ran through the OEM Bridgestones in only 7500 miles (not sure what happened there...).  Didn't necessarily want some true sport rubber, just something that would last a while longer.  Seeing as I have no job at the moment, cost was definitely a factor as well.  Plus I don't really want to invest a lot into the GS.  Near stock is how I like things - makes you learn to make the most of what you've got.  Only mods I plan on doing (and have done) are suspension upgrades to improve stopping and overall ride quality.

[Alphamazing]

Thing there is the $$.  I wanted higher quality rubber and wanted to get a little bit wider, but didn't want to add the cost of a new wheel on to that.  I ran through the OEM Bridgestones in only 7500 miles (not sure what happened there...).  Didn't necessarily want some true sport rubber, just something that would last a while longer.  Seeing as I have no job at the moment, cost was definitely a factor as well.  Plus I don't really want to invest a lot into the GS.  Near stock is how I like things - makes you learn to make the most of what you've got.  Only mods I plan on doing (and have done) are suspension upgrades to improve stopping and overall ride quality.

The difference between a 140 and a 130 is... minimal, really. Especially when considering looks. Even a 150 looks tiny compared to a big 180 on a modern sportbike. Honestly, if it's just about looks, why pay more for a 140 when it still looks like you've got a tiny back tire. You're better off getting a set of Sport Demons in the stock sizes and enjoying the new-found stickiness, as they are better than the BT-45s that come stock.

And the Katana wheel swap is not necessarily expensive. You just have to look around and be patient.