Finding actual tire width specs?

[Steve]

-Current rear tire is a bridgestone 130/90 17" on the factory cast 2.5 wide GS mag. Tire wise, I don't intend to go much bigger than that....BUT....swapping to a radial on an inch wider rim is why I'm asking for tire and width suggestions since that's new territory for me...I hope that some here have gone a similar route on their modded GS bikes and can lend some input.

You DEFINITELY want a wider wheel when you go with radial tires. 3.5" <might> be enough for your 130. If you could find a 4.5" wheel, it would be even better.

Even going with a wider rim, until you get a rim that is wider than the tire, it won't change the overall width of the tire. Your 130 tire will still measure 130 across the edges.

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[80GS850GBob]

The whole back end is made for a 130 tyre. where you slide the tyre in between the diff and swingarm isnt much room left when u have a 130. You say u want 18" radial, once again u struggle with a 140 and even then the profile be only 70% of witdh so the whole bike would squat in the rear limiting ground clearence. And where you finding spoke wheels unless ure paying for expensive custom hub? Have you priced the cost of hub, spokes and a 3.5 x 18 rim? Be worth more than what u buy a average 850 for.

A "140" what tire?....what tire aspect are you referring to? A 140/90 would yield a 126 side wall...but a 130/90 would be 117...still leaves the tread area thickness though...but even then roughly 9mm lessor height won't break the bank on cornering nor clearance between the two of them. The bike. however, is currently sporting a 130/90 17" biased ply rear now and if I dropped to a 130/60 17" radial that'd be a 39mm drop total OD{1.5"ish for half} and that's why the thought of an 18" hoop...would be an inch drop which isn't terrible.

...no custom hub...I could, but nope. VS800 shafty rear wheel just for the hub {w' drum brake} {$58 shipped/ebay}{same part number drive spline}...'04 cable actuated drum brake assy for flexibility to attach to the rear sets {$32 shipped/ebay}.
...A new 17"-18" hoop runs $180-$230...new s/s spokes should run $170ish...should be a tad less for the front wheel cost using my GT750 hub there.
...I paid $1100 for my clean 850G w/13k and it was worth it...only $575 for my 1000G{30k}...and slowly counting to get her to where I want. Sorry, maybe the GS bikes are cheaper by you...

[80GS850GBob]

You DEFINITELY want a wider wheel when you go with radial tires. 3.5" <might> be enough for your 130. If you could find a 4.5" wheel, it would be even better.

Even going with a wider rim, until you get a rim that is wider than the tire, it won't change the overall width of the tire. Your 130 tire will still measure 130 across the edges.

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Ah...that's the angle I was getting at! Radials need a wider rim. I can only, easily, fit a 3.5 rim back there and there's no intermediate size other than a 4.25 next {sucks}. A 4.25 would not only yield only an 1/8" clearance to the swing arm {rim edge to arm} but would also require the whole drive hub removed to change the tire...ugh....even though tire changes aren't that often, I wouldn't do that to myself-lol.
To think - keep a 130 tire at a matching rim width is ok, but not finite...to fudge a little wider or narrower rim can change the tire profile..but is that good or bad? I need to learn this...

[80GS850GBob]

How well will that align with the front wheel? I believe The bead area of a bias ply and radial are quite different but I suppose you could run a tube.

The VS800 hub is offset slightly to keep alignment...while I have to remeasure all that I intend to install back there, the base centerline should still be the same and needs to be the same so as not to affect handling.
And you are correct...radial rims have a larger internal notch {for lack of better words} to anchor the tire while the biased ply rims do not have as large an internal notch.

edit- yeah, I'd have to run a radial tube {yes, there is such a thing}...to do so on a radial though is to downgrade the speed and load rating by one notch/step because of the tube.
Add a healthy dose of talcum powder in there too...see my old car/other wife...I'm used to inner tubes

[80GS850GBob]

I ran a 150 on my red gs when i swapped to the 3.5x17 from the vx800... also with a spoke wheel he could set the rim slightly off center.. not that itd need it. There was about an 1/8 between my tire and swing arm

I forgot that rim of yours was a 3.5 wide.....do you happen to remember what the rim clearance was to the inner arm with that 3.5?

[80GS850GBob]

OK go for it. use a 3.5 rim with a 140 or 150 tyre. Ill grab a chair and have a sit down and wait.

The best for last today...lol
A} I asked about actual widths...don't believe I ever said I was gonna run anything yet...still trying to figure out intended tire widths compared to what I know I have to work with.
B}...was that a 140-150 radial tire or biased? I'm already in my comfy chair...you should be too...

[Steve]

Ah...that's the angle I was getting at! Radials need a wider rim. I can only, easily, fit a 3.5 rim back there and there's no intermediate size other than a 4.25 next {sucks}.

At least a 3.5 rim is better than the stock 2.5.

Over on the Goldwing forums, there is a lot of talk about going "darkside" by putting a car tire on the back of the bike. That is mostly on the 1800 Wings, starting with the 2001 models. The rear tire is a 180/60-16, I don't remember what the rim width is. I was curious about trying that with my 1500 Wing, but there was very little discussion on that. Finally found a few threads and gathered information on what tires they were running. The stock tire on the 1500 Wings is a 160/80-16. Note the difference. Narrower and taller than the 1800 tires. The rim on the 1500 is also about an inch narrower. Well, I tried it. found a tire that was narrow enough to fit my narrow rim. It has an incredible weight rating and is designed for light commercial use (London taxi), so it might work. It is a bit taller than a stock tire. I have to run maximum air in the shocks ALL the time, or the tire rubs on the inside of the fender, especially if I am carrying a passenger that is large enough to cast a shadow.

The really sad part, and the point of this post, is that I have to increase the air pressure in the tire to get any kind of stability. You would think that with a larger carrying capacity, I would not need to add as much air to carry the same load, but the rear end of the bike felt like it was riding on Jell-o. I have to run the pressure near the max of 55 psi, and it still feels squirrelly. Mostly because the rim is not wide enough to properly support the radial tire.

That tire should have given me 40-50,000 miles of service. I think I have about 3,000 on it, I will be changing it before doing much riding on it next season.

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[80GS850GBob]

Ah...there's the rub...terrible pun, sorry.
While a given tire has the capability to run on, say, three different rims...it's usually going to best suited on only one. That is also indicative of what cycle its on as well...depending om what clearances "that" bike has for said tire. A lot of variables to consider.

On a correct rim, brand A runs a few mm skinnier than width spec while brand B runs a few mm over width spec...brand C could distort terribly on the same rim since their tire chart is waaay off.

You'll laugh at this comment, and that's fine...but just because you can do something to a motorcycle doesn't mean you should {or could}.
...and I'm not fully convinced that rear shocks one inch longer would tear up the uni because of the slightly added new angle - but untill someone tries it and confirms...who knows more than random speculation...

[Steve]

...and I'm not fully convinced that rear shocks one inch longer would tear up the uni because of the slightly added new angle - but untill someone tries it and confirms...who knows more than random speculation...

I am hoping that one inch doesn't make much of a difference, but we are doing it in the other direction. We got shocks one inch SHORTER for my wife's 850L. I figure that it's no worse than stock-length shocks with sacked springs and riding 2-up, the ride height will be the same.

I have not analyzed the actual driveshaft angle to see where it is perfectly inline with the secondary drive and how far it swings on either side of that straight line. My guess is that it might be straight with stock shocks compressed about an inch of their 4-inch travel. That way, when the suspension moves, it will stay relatively straight. For the occasional times you have the load of a passenger, the additional angle should still be within allowable limits. Using longer shocks will probably keep the same angle, but in the other direction, which shouldn't be a problem.

And, if you really get down and analyze the situation, it might not be the u-joint that fails. The whole reason this issue exists is because the u-joint is a simple, single joint. As the angle of the driven shaft increases away from straight, its rotational velocity changes twice in each rotation, due to the action of the yokes in the joint. The u-joint is at one end of the shaft, but the gears in the final drive are at the other end. What's to say that THEY won't be the ones to fail first? In fact, maybe the ring and pinion actually hold up quite well, and transmit those speed variations to the SPLINES, causing THEM to wear?

Something to think about.

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[80GS850GBob]

I am hoping that one inch doesn't make much of a difference, but we are doing it in the other direction. We got shocks one inch SHORTER for my wife's 850L. I figure that it's no worse than stock-length shocks with sacked springs and riding 2-up, the ride height will be the same.

I have not analyzed the actual driveshaft angle to see where it is perfectly inline with the secondary drive and how far it swings on either side of that straight line. My guess is that it might be straight with stock shocks compressed about an inch of their 4-inch travel. That way, when the suspension moves, it will stay relatively straight. For the occasional times you have the load of a passenger, the additional angle should still be within allowable limits. Using longer shocks will probably keep the same angle, but in the other direction, which shouldn't be a problem.

And, if you really get down and analyze the situation, it might not be the u-joint that fails. The whole reason this issue exists is because the u-joint is a simple, single joint. As the angle of the driven shaft increases away from straight, its rotational velocity changes twice in each rotation, due to the action of the yokes in the joint. The u-joint is at one end of the shaft, but the gears in the final drive are at the other end. What's to say that THEY won't be the ones to fail first? In fact, maybe the ring and pinion actually hold up quite well, and transmit those speed variations to the SPLINES, causing THEM to wear?

Something to think about.

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I'd be willing to bet there's a +/- 1" bit of flexibility built into the drive system...otherwise how many GS G's would be dead from touring weight/drive line issues?!
{-edit...engineered flexibility as in sustained drop with rise for dips in the road}
To reasonably assume that up to an inch of regular deflection is to be expected while riding even one up, due to road imperfections, it just has to be assumed as figured in for by the factory {see above to confirm}...the question is will long term deviation from the intended oem drive line centering be an issue...time would/will tell.

Was just tossed this tire size comparison link from another forum...pretty neat. Try it to see the difference in height between tire sizes..

https://www.tacomaworld.com/tirecalc?tires=130-70r18-130-60r21

[thebrandonbeezy]

I think i have the measurements on photobucket, ill check

[Steve]

Was just tossed this tire size comparison link from another forum...pretty neat. Try it to see the difference in height between tire sizes..
https://www.tacomaworld.com/tirecalc...0r18-130-60r21

I don't remember which vendor it was, but one place I was shopping for tires had actual mounted dimensions for tires. It would not do much for comparing how much a tire changed by switching to a wider rim, but it was rather interestingn to see all the different dimensions for the same size tire.

Mathematically, a 130/90-17 tire should be 26.21 inches tall. I don't remember the brands involved, but one tire might have been as short as 25.5", while another might have been as tall as about 27".

There were also similar variations in the width, I just found it amusing that they all claimed to be the same size.

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[80GS850GBob]

Oh yeah...MC tires are like shoes...they aren't all the same no matter how the size is listed...and add a different rim under it and you can change the profile yet again!

...just emailed the rim vendor I like for actual width specs on my two rim choices for the rear. The answer will determine which I can use as far as realtime clearance is concerned....and yes, it'll most likely be the 3.5 wide rim but there's the off {waaay off} chance the 4.25 might work. Hope springs eternal though....lol.

If I wind up with front and rear 3.5 wide rims I'll have to get two radial "front" tires since actual rear radial tires like to start at 4.00 and on...sheesh...

[80GS850GBob]

I think i have the measurements on photobucket, ill check

I just emailed Warp 9 for real time rim widths....I'll get an answer soon, I hope, as to which one can be used in my application. Then...the color choice begins!
Wish more companies ran 4.00 or even 3.75 rims for spokes...

[Steve]

If I wind up with front and rear 3.5 wide rims I'll have to get two radial "front" tires since actual rear radial tires like to start at 4.00 and on...sheesh...

If you mount a "front" tire on the rear, be sure to turn it around so it rotates the "wrong" direction.

Not sure how long a front tire will last on the rear. In the Wing world, it's more common to mount a rear tire on the front, especially for trikes.

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