Rear tire feels unstable in turns

[gstam4]

hey all - seems my leaking-gas and other mechanical problems have been fixed, so i'm moving on to the next one on my list.

i have tires with plenty of tread, and the air pressure is good. they're a little on the old side (mid to late 2008), but don't show any signs of rot. if i decide to keep the bike past the summer, then i'll probably replace them.

when i take a turn with even moderate speed and lean the bike a little (i mean really a little - even if i'm doing a right-hand turn onto another street at 10 mph), the back end/tire feels 'unstable' - as though it's sliding, even though i know it's not. it's hurt my confidence in turns, because i'm worried the bike will slide out from under me. i don't have any stability problems riding in a straight line, other than getting blown all over the place by the wind.

assuming my tires have proper pressure and aren't themselves the problem, anyone know what it might be? i saw 'trail number' mentioned online somewhere, but not in relation to a gz.

[Water Warrior 2]

Trail numbers refer to front end geometry. You may have a faulty tire pressure gauge and are actually on the low side of the recommended PSI. I would however plan on new tires soon. After 5 years the rubber is harder and slippery even on the best surfaces. Be really careful during a rainy day.
A hint for better tire mileage is to run with 2-up pressures all the time. The handling will not suffer and there is slightly less rolling resistance from the rear tire.

[jonathan180iq]

I agree with this. I had a very similar feel and could not figure out what was going on until I got brave in a turn and just leaned out and over to see what the hell was going on. Turns out that despite what I thought, my air pressure was not accurate and my front tire was giving in turns. Have someone watch you or record yourself on video if you have to. (just find a cul-de-sac or something) All of your descriptions sound like air pressure. Even a hardened older tire won't give like that unless the road is wet or glassed from heat.

[gstam4]

thanks guys, i'll check with a gauge (instead of eye-balling and feeling with my hand) and see if that helps.

as far as buying tires, how do people do it? i think i remember reading on here that it's hard to find a matching set? any brand recommendations?

[jonathan180iq]

Whoa.

Definitely use a gauge. You can be off by double digits with the old hand test and not ever know it. Once loaded with your body weight, the way a tire feels is going to be very different from what you feel with your hand on the tire and no weight on the bike.

My issue was a faulty schrader valve. If that happens to be an issue, then I have a poor-man's method for swapping those out too.

[gstam4]

so, uh, apparently the front tire was at 44 psi, and the rear at 42. the bike is sitting in the 90-degree sun, but hasn't been ridden for about 2 hours. i tested my car's tires using the same gauge, and they were at about 33 psi, where they should be.

this is how the dealer (from whom i bought the bike, and who has had it back numerous times for repair, including about 2-3 weeks ago) inflated the tires for me. i haven't touched them myself.

bad?

update: i dropped both tires down to about 33-34 psi and rode around a bit. maybe it feels a little better, but i think i still feel at least some of the instability. time for new tires, or is there anything else it could be?

the tires themselves really look great. no center wear, etc.

[Water Warrior 2]

Ideally you should check the tires cold(unridden)in the morning and before the sun warms them.

[Cathy]

Qasual - Replace your tires, they're passed the lifespan of the average tire (4-5 years) also the tire pressure should be 28psi front and 30 rear (32 is two-up).

I'll take a picture real quick of the sticker. I may be off by 1 psi or two, nothing to worry though.

[gz4me +]

My sticker on bike and the manual says: Solo Riding- 25psi front 29psi Rear. Dual Riding 25psi front 33psi Rear. Hope this helps.

[gstam4]

thanks again.

trying to figure out what tires to buy to replace them, i just saw that while my rear is a 130/90-15 (which seems right), the front is a 120/80-16 (whereas the book says it should be a 110/90-16). is that a problem? can i buy either size as a replacement?

[gz4me +]

Manual states 110/90-16 59P for the front 130/90-15M/C 66P for the rear. Also states: The use of tires other than those specified may cause instability. It is highly recommended to use the specified tires. I have always gone with what the manual suggest. Perhaps there are others who have not and can advise if they had any issues.

[JWR]

The 100/90 on the front will work o.k.

[jonathan180iq]

Ahem...

Modifying the GZ - What's Available?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

There aren't many tire options for our bike that come in a matching set. There are, however, many options if you don't mind mixing up tire brands and/or going to a slightly smaller tire up front.

The factory tires sizes are: 110/90-16 (F) & 130/90-15 (R)

The rim width for the front wheel is 2.5" and the rear wheel width is 3.0"
That being the case, a size 100/90-16 front tire will work on this bike. It does have an overall diameter decrease of 9mm over the 110/90-16 but that isn't really very drastic.

Samato has verified that alternate tire size 100/90-16 will mount up with no problem.

As well, the 120/80-16 alternate tire size is another choice for the front tire and has been successfully mounted by MRLMD1.

Factory replacement tires: 110/90-16 & 130/90-15
Dunlop D404 (only available through a Suzuki dealer)
Metzeler ME77 (only available through a Suzuki dealer)
Cheng Shin C906 & C907 (possibly no longer available)

Rear Factory Replacements:
Kenda Challenger
Pirelli MT66 (Route 66)
Maxxis M6103
Cheng Shin Marquis
Metzeler Me 77

Factory Replacement Front:
GBC Green Shark
Metzler Lasertec
Pirelli Sport Demon
Avon Roadrider AM26
Conti Ultra TKV11
Kenda K671 & K673

100/90-16 Front:
Bridgestone BT45
Maxxis M6002
Cheng Shin C6000
Kenda Cruiser
IRC Durotour

Matching tires with low profile front: 100/91-16 & 130/90-15
Kenda Cruiser

[5th_bike]

It could also be alignment. A quick check for alignment is to drive with your hands off the steering (where appropriate, if your comfort level allows, etc.). If you have to lean left or right to keep the bike going straight, your alignment is off.

[Water Warrior 2]

It could also be alignment. A quick check for alignment is to drive with your hands off the steering (where appropriate, if your comfort level allows, etc.). If you have to lean left or right to keep the bike going straight, your alignment is off.

Just to expand on the above statement. Alignment could be front or rear of the bike. The rear due to not doing a proper chain adjustment and the rear adjustment marks are not the same distance on both sides of the swing arm. This will have the rear tire slightly cocked to one side and it will not follow the front in the same path down the road. This will also accelerate chain and sprocket wear too.
The front could be out of alignment because the forks are slightly tweaked and will need to be adjusted to match each other. If the bars are not totally aligned with the front wheel, such as being slightly left or right when riding in a straight line you will need to investigate further.

[jonathan180iq]

Can you check your rear wheel by making some DIY rear fork stands and elevating the rear tire off the ground. (There is a link to making these on the maintenance page)

Once elevated, just start the bike a let the engine momentum turn the rear wheel while you watch it. Check the alingment marks on the rear axle nut, and check the rear axle nut for proper torque. These are all covered somewhat in the front sprocket replacement guide as well.