I'm new, got a question (tire size in rear)

[jeff721]

Hi, my name is jeff as my s/n implies. I'm from MD and actually work at a cycle shop (but I'll be quiting soon). I've got a question for you all though, I'm trying to get my GS on the road and the only thing stopping me is my rear tire being dry-rotted. Now, I want to have my bike on the road by this weekend, and can't find a back tire that fits.

Now I know people normally want to go the other way, but can I put a 120/70-17 tire on the rear? I've got tons of them hanging around and could just throw one on until I could get a 130/70-17.

Thanks for your help, I'll post pictures of the bike that I just totally rebuilt soon, i't not quite done yet.
Jeff

[Trwhouse]

Hi Jeff,
Welcome to our community.
About the rear tire size ... don't put an undersized tire on the bike. Put a 130/70-17 on there as soon as you can and don't go undersized.
The reason -- an undersized tire won't have the weight carrying capabilities of the proper tire and it won't have the proper shape and profile for good handling especially while cornering.
It's not worth the risks.
Besides, no motorcycle shop would ever put an undersized tire on a bike unless they are a scumbag shop (well, that's possible of course) that was out to rip people off and not be concerned about their safety. A shop that would install an undersized tire would certainly be liable for damages if the rider were injured due to undersized tire being installed by the shop.
Do it right and then there won't be any problems.
Good luck,
Todd

[runsilent]

If you have tons of 120/70/17 tires hanging around, they must be front tires.  Can't think of any 120/70/17 rear tires.  It's really not good to put a front tire on the rear.  A 130/70/17 has a 584# load rating and a 120/70/17 has a 520# load rating.  The GS500 has a load rating of over 400# so it wouldn't be a problem load wise if you're not carrying a max load.

What do you have available in rear tires?  A 130/70, 130/80, 130/90, 140/70, 140/80, and some 150/70 sizes would fit and would be better than a front tire.

If you were to try a front tire temporarily on the rear, you should reverse the direction of rotation.  Front tires are designed for braking forces and rear tires for driving forces.  A few universal tires that are made generally have two rotational arrows on them, one for front and another for rear application.  Front tires have less tread depth. I'm not saying I wouldn't try it in a pinch, but I'm not suggesting you try it.   

[Turd Ferguson]

If you have tons of 120/70/17 tires hanging around, they must be front tires. 

Exactly, they must be front tires.  DON'T put a front tire on the rear of your bike.

-Turd.

[jeff721]

Thanks for the advice, I decided not to go with it for the purpose of not sealing/ not being safe/ and not being a rear tire. I should hopefully have a rear tire in by tomorrow and on my bike with a new chain.

But again, thanks for all the advive. Glad to see it's an active community around here.
Jeff

[Alphamazing]

Actually, you can put a front tire on your bike. Just turn the tire around so the tread is going the other way. 120/70-17 on a 3.5" wide rim is the fitment approved by most manufacturers, I believe.

I know there is at least one guy who did it on here.

[TragicImage]

I think he made the right choice in waiting for the proper tire.

[pantablo]

in a pinch you could go with a 150/60 rear.

[Turd Ferguson]

in a pinch you could go with a 150/60 rear.

The key word there being "pinch" because the stock wheel will pinch the hell out of a 150 and change the profile completely.

-Turd.

[jordanearl]

i run a 150 pirellie dragon supercoursa, an have no ill effects. 

[gsJack]

I put a pair of Lasertecs on last Oct in the 110/80 and 150/70 sizes and this was my first 150 on a 3.5" wheel, a fitment approved by Metzeler.  It was pinched a bit as expected but not to any extreme, actually it took a shape like a 190 tire does on a 5.5 rim, also an approved fitment by tire makers.  Take a look at this diagram and pics from Sport Rider tech talk on tires:

http://www.sportrider.com/tech/tires/146_0206_tire_size/

It quickly took the shape of the 190 on a 180 wheel and the center tread depth then measured 1 mm less than it did in the grooves just off center to confirm that change of shape.  After the initial reshaping wear, the tire wear progressed slowly, the handling was very good for street use and was just about as good as the sport touring radials I've tried. It never showed any ill effects like falling in that has been reported for the 150/60 fitments when worn and which are not approved fitments.  They had 10k miles on them and a bit to go when I repace the rear with a 150/70 Conti RoadAttack.

I'm now running a pair of Lasertacks (patt pending:-), the best ever so far.  Yeah, I know you've heard that before.    
I'm running the 110/80 Lasertec front with the 150/70 RoadAttack rear and it is excellent.  I've long been a fan of the Metz Laser type tread pattern and the new Conti is the stickiest rear I've tried, nothing has upset it so far.  Conti claims they have supersport grip with sport touring life.  I can now confirm the grip part and hope it's next year before I can confirm the life part.   

I consider this to be a matched pair now, Metz bias Lasertec front and Conti radial RoadAttack rear; they're both made in Germany, right?  I think I'll be sticking (pun intended) with these forever............................or at least till something better comes along.   

As always these are my opinions on sport touring tires that have a good balance of handling and tire life and I will leave the opinions on the supersport tire performance to others here that actually use them.  If I ever win the lottery, I'll give them a try or perhaps when my annual milage gets down to a few thousand a season.   

[TragicImage]

Jack... good to see you back under this name.


What Conti supplier are you going through?  Anyone you can reccommend?  I'm probably looking for a new set, even though I just put some Sport Demons on, I'm not entirely satisfied with them.

[WREX]

Jack - welcome back as gsjack again.

Any clearance issues with the RoadAttacks in 150-70?  anything have to be changed from stock?

[gsJack]

What Conti supplier are you going through?  Anyone you can reccommend?  I'm probably looking for a new set, even though I just put some Sport Demons on, I'm not entirely satisfied with them.

Any clearance issues with the RoadAttacks in 150-70? anything have to be changed from stock?

I bought my RoadAttack and my Lasertecs from Shade Tree, a mail order place with a small retail store located about 30 miles from me that charges only $19 to mount and balance carry-in wheels including a new valve stem and disposal of the old tire.  Good deal if you live near here, but I've never done any mail order business with them.

http://www.shadetreemotorcycle.com/

I usually suggest AMT or Southwest for online tire purchases; I have bought from both.  Tires Unlimited just added the RoadAttacks and seems to have the best price right now.  Haven't tried them but a friend gets tires from them and likes them.

http://www.americanmototire.com/
http://swmototires.com/
http://www.tiresunlimited.com/

As far as the clearance issue goes, I didn't alter anything to accomodate the RoadAttack; but it's just about touching/maybe touching the brake torque rod.  According to published figures, it should be the same width as the 150/70 Lasertec it replaced and also the same width as the 140/80 AV36 on my old 97 GS.  But both the Lasertec and the AV36 have/had a few mm clearance; the new RoadAttack is appearantly a tad wider.  I managed to pull the axle and put it back w/o changing the adjustment screws between tires so that doesn't account for the diff.

Got about 400 miles on it now and think I'll go a bit more before pulling the brake rod to see if it's actually rubbing; if it's touching, I'll get out the BFH and adjust the rod a bit.   

[werase643]

yes you can put a front tire on the rear
it just looks really tarded
the tire doesn't know which rim it is on
and yes back in the day you swapped direction of rotation.....

most fronts are low profile....therfore the gearing effectively changes also

[Fast Jetta 97]

SO, question... i want to get a new rear tire... but i hate how the stock one looks....
i wanna go wider and lower profile than stock, what is the max i can go it both ways.

stocks = 140/70...
can i go = 150/40... lilke what is the lowest pro i could go and how wide will the stock rime hold without problems.

and if i go lower profile will it change anything besides the looks?

[NiceGuysFinishLast]

Stock is 130/70

140/70 is doable

150/17 is pushing it, and you will have issues with the brake torque arm, it will need to be bent. This has all been covered. Check the wiki, or search the site.

Edit: If you're just worried about looks, you'll need to buy a 4.5" rim from a katana or gixxer, and fit it up and put a 150 on that. Or just drop $8K on a gixxer600.

[gsJack]

150/70/17 Conti Road Attack radial on stock 3.5" rim on my 02 GS500:



Had to bend the brake torque rod a bit for clearance.  Previous 150/70/17 Lasertec fit w/o bending brake rod.

Widest and lowest tire that would be practical on the stock 3.5" wheel would be the 150/60/17 supersports; not a tire mfg approved fitment, but many are running them on GS500 and 94 and later EX500 (Ninja).

[TragicImage]

I took have/had the Conti RoadAttack.


Good tire, fits "OK"... I actually had a notch welded out of my brake arm.... works ok.

[Fast Jetta 97]

i just basically wanna know whats the "lowet profile" tire i can run on the back with no problems...

anyone know a good place to get motorcycle tire ( i need a new front and rear)....