Rim size recommendations

[Chuck78]

In tires, I ABSOLUTELY LOVE the economically priced Shinko tires in a 230 TourMaster 100/90-18 front and SR741 140/70-18 rear. You will only get 4,000 miles out of the rear, but wow these tires grip AWESOME! Especially for the $130-ish price tag for both, SHIPPED TO YOUR DOOR! The rear will definitely gave a flat patch worn down the middle of the tread at 3,000mi though



This time around, I around trying around mix& match with a 100/90-18 Shinko front and 130/80-18 Bridgestone Battlax BT45V rear. I am doing this in trying to overcome the shortcomings of each. The Shinko rears wear rapidly, & a few Battlax users (not all) complain of weird handling quirks on their fronts, resulting in an uneven cupping treadwear pattern. Could be tire pressure related? The shinko front I believe will do better in the rain. The Battlax BT45 rears have "Sport SACT" technology - a dual compound rear with extra grippy soft side tread and slightly harder compound down the middle so that they wont wear flat as quickly. They still wear much faster than an Avon AM26 Road Rider, but the grip is undeniably better than the Avon street tires. I will report back on my findings.

I also am doing these particular sizes this time around as an experiment to see if running the narrowest recommended sizes on my wider Sun rims will slightly flatten out the tread profile enough to give me an increased contact patch and more traction! I can never run the "best recommended fit" tire sizes leaning all the way over to the edge of the tread without scraping hard parts anyway, so it seemed logical to me. It was a tough call vs a very affordable and superbly constructed Shinko SR741 rear which I know will be an EXCELLENT performer.

The Pirelli Sport Demon in a 140/70-18 rear and 110/80-18 front will hands down be the most phenomenally gripping tire in wet and dry conditions, you should really try these out, but the rears wear pretty quickly too. They are supposedly designed now (newer ones in the past 2 years) to not wear down as fast on the center of the rear tread but these are an extremely sporty tire, so it's going to wear fast regardless.

I don't like the Avon AM26 as much as most people talk about, as I have had the rears step out on me quite a lot the way I have been riding in the past 5 or 6 years. Last season the front slipped slightly on me twice at hard lean angles, which scared the $#!+ out of me! Luckily it was very minimal but enough to tell me not to run these if I continue to push the limits of cornering ability in the amazing Appalachian hills of SE Ohio / Eastern Kentucky / all of West Virginia...
The Avon Road Riders are great if you don't want to change tires often or if you so mostly city and highway miles. Best cornering grip for a better treadwear lifespan tire

[sharpy]

we run Akront rims. Best around and rear matches the new front exactly. pretty sure you can still buy them but in australia there around 600 for a rear rim.

[Chuck78]

I just picked up a bunch of Akront TC and TR rims for 2 race bike projects.
TR 4.25x18 40h and 2.15x18 36h for the Rickman/Scarab hubs I have for the Rickman CR chassis with a monster 1105cc bored and stroked GS1000 engine I have here in pieces. I really am searching for a 2.50x18 front Akront TR rim though. They are hard to find so I may strip the anodizing off of a DID 2.50x18 and polish it instead, as it has a similar slight flanged lip at the bead like the Akront TR.
I got a 1970's NOS 2.75x18 rear from ebay.it and 2.15x18 front newer old stock (5 year old Morad reproduction) from a guy Charlie in Idaho that has like 3 or 5 more on ebay now that would probably fit a GS front hub fine, he doesn't have 36 hole rears for us though but his front 2.15x18's are incredibly priced at around $140-ish shipped I think I gave him. Basically same rim as the Excel but bare polished aluminum not clear anodized. This will be the race wheel set for the GS425-489cc project, as I am limited to 3.00" rims in WERA Formula 500 class rules.

[storm 64]

Great advice Chuck, I was hoping you'd chime in. I was getting ready to call you. I'm not not sure how the 18 inch front would look under my big chrome fender... I'm still waiting on Woody from Woody's Wheel Works in Denver to get back to me with a price quote. And yes, I did machine the ribs off. Just to smooth everything out. I don't think I "butchered" it up to bad. Lol.

[Chuck78]

Great advice Chuck, I was hoping you'd chime in. I was getting ready to call you. I'm not not sure how the 18 inch front would look under my big chrome fender...

the 18 will look totally normal up front in a wider size, as the wider tread width tires will be substantially larger in diameter in a 19" size than a stock 3.25-19 tire or whatever they were, and one thing you absolutely want to avoid is sticking with the same overall diameter front tire - YOU WANT TO GO SHORTER OVERALL FT TIRE DIAMETER as they do steer a little sluggish like the most sporty of Hardly-Ablesons do stock. Front tire diameter is the biggest factor in steering trail. #2 is the rake of the frame, which can also be steepened to decrease trail by taller shocks/shorter fork installed height, & taller diameter rear tire / shorter diameter front tire. Getting down from a stock 4.21" trail spec to a 3.9" or so range will make that the steering responsiveness of that big 998cc beast handle like a dream, as if you dropped 100lbs off the bike.

I was running 110/90-18 fronts which are basically the same diameter as a 3.25-19, but I am done with that size, they look too tall and don't steer as quick as a 110/80-18 or 100/90-18.

Also I'd look into some YSS G-302 shocks with the adjustable ride height clevis so you can dial in the steering feel better. Those are an excellent bargain at around $500 with adjustable damping. Works also has some Street Trackers in the same price range.
While you have the front wheel off, YOU GOTTA upgrade to Racetech gold valves and Sonic Springs... your GS1000 will be the sweetest thing around with all of these performance enhancements! Stainless brake lines and new pads, too. Or just do the popular twin pot brake mod. You can get some decent 296mm Chinese 98-99 cbr600f hornet rotors that are black centers and a direct bolt on with no spacers (after u drill the bolt holes from 6mm to 8mm).


****I edited my above posts and added more info, you may want to refresh your browser and re-read.

[Chuck78]

Steering Geometry info

Here ya go Norm, I use this info all the time when crunching steering geometry numbers based on tire diameters. This also tells you at least the most recommended fit of tire size vs rim width, most manufacturers tell you best fit and alternate acceptable sizes/fitment above and below the best fit.



This Pirelli screenshot is THE ONLY detailed Pirelli info I could find on the net, I think it was only available on the Canadian Pirelli site.


Here's the Avon AM26 Road Rider specs:

http://www.avonmoto.com/products/street-bias/roadrider

note that the Avon tires run wider/taller than any other brand in the same size, so their diameter listing on your original OEM 3.25-19 front is probably going to be taller than the original equipment 1978/1978 front tire was when they advertised the rake and trail specs in magazines.

Bridgestone info, you want the BT45V. The standard H-rated (112mph) BT45V comes mostly in vintage stock sizes, the V-rated (149mph) BT45V comes in sizes for aftermarket wider 18" front and rear rims:

http://www.bridgestone.com/products/motorcycle_tires/products/size/result.html?reset=1&c%5BItem.search_size_rim%5D%5B1%5D=&c%5BItem.search_size_rim%5D%5B2%5D=18&c%5BItem.search_size_rim%5D%5B3%5D=&c%5BItem.search_size_rim%5D%5B4%5D=

that is only a search listing for 18", so the limited 19" front sizes are excluded from that
here's the 19", basically only choice is stock 3.25-19 or exact same width and darn near exact same height 100/90-19:

http://www.bridgestone.com/products/motorcycle_tires/products/size/result.html?reset=1&c%5BItem.search_size_rim%5D%5B1%5D=&c%5BItem.search_size_rim%5D%5B2%5D=19&c%5BItem.search_size_rim%5D%5B3%5D=&c%5BItem.search_size_rim%5D%5B4%5D=

You really should upgrade the width to a 110/80-18, gives you ~12mm more tire width but shaves off 13mm in radius, which won't be much of a noticeable difference to the fender clearance up top, but on the bottom you lose another 13mm radius which helps reduce your trail by radius alone and also as a result of dropping that 13mm in front ride height you steepen the rake a slight bit, which also makes the steering more sporty which also reduces the trail spec ever so slightly


Here's the Shinko 230 TourMaster front specs if you go with a 100/90-18 on a 2.15 or 2.50 or 2.75 rim:

http://www.shinkotireusa.com/tire/230-tour-master

and the Shinko SR741 rear specs for 140/70-18

http://www.shinkotireusa.com/tire/sr-740-741-series

Click on the sizes tab, & then click on the individual size selection to expand it to see the fitment/width/diameter info
***I noticed the Shinko SR741 does come in a 150/70-17 if you went 18" front 17" rear rimes. These are phenomenal gripping tires for the price but do wear faster on the rear. Pirelli also offers a 150/70-17. Avon and probably Bridgestone as well. Compare the OEM spec rear diameter to those... going 18" rear will change the gearing and add and little weight, but will quicken the steering additionally, which you will be very pleased with if you can get a steeper rake and slightly shorter front tire that gets your trail down below 4.00" to as low as 3.85". 3.74-3.78" is road rake ace territory and probably needs as steering damper.


I have a hunch that a Battlax BT45V or Road Rider in 140/80-18 may be the best choice with aesthetics in mind - although for total performance, the 140/70-18 and 110/80-18 Pirelli Sport Demon combo will be the best. The 140/70 is a bit low profile (130/70 is too short aesthetically, I won't run one on a big bike) & I always liked the taller look of the 150/70 better, but the chain is darn close to it and makes contact occasionally without offset sprockets. The 140/80 is a hair taller than a 150/70. But no PirellI or Shinko option in 140/80, only RoadRider or Battlax BT45V

[Chuck78]

More geometry info

And here is what I use to figure up how the tire and suspension changes affect the rake and trail:

https://www.rbracing-rsr.com/advchoppercalc.html

forgive that it's a Pukely-Davidson chopper website, this calculator does the job well

The rear tire diameter box doesn't do much for some reason. In order to figure in how ride height changes affect the rake and trail due to shorter forks, taller/shorter shocks, taller/shorter tires, I manipulate the "new fork length" data field to give me the figures I want. Not 100% accurate since the forks and shocks are not 90 degrees vertical but darn close enough. Perhaps there is a better online calculator out there besides buying Tony Foale's frame geometry software, but this does the job well enough. For taller than stock rear tire diameter I SUBTRACT the rear tire RADIUS from the "new fork length" field to get the proper manipulation of the adjusted rake. Shorter than stock rear tire I add the radius. Same goes go the front tire and fork height, subtract radius or fork height drop to get the "new fork length" field entry with tire changes added into the rake calculation modifications.

[sharpy]

I really am searching for a 2.50x18 front Akront TR rim though. They are hard to find so I may strip the anodizing off of a DID 2.50x18 and polish it instead, as it has a similar slight flanged lip at the bead like the Akront TR.
.

Cant you use a standard GS1000 Rear rim. Pretty dam close to a Akront... Also use 140 X 18 BT45 rear tyre as i found it suits me well. No chicken stips and just using the throttle on a uphill wet road will pick up the front wheel to balance point. Most others just fishtail. Forgive the front tyre, bike has been parked for over 5 yrs

[Chuck78]

Sharpy, I think you meant "can" not "can't"
Norm has a GS1000E with 17"/19" mag wheels, not a GS1000C/N with wire spoke wheels. I think a lot of the US GS1000C models still had a 2.15x18 rear but got upgraded to a 2.50. The spoke angle drilled into the rear GS1000C/N alloy rims is not quite right for the substantially smaller diameter GS front hubs angled should really be drilled out oversized to the proper angle and fit with larger spoke nipple to accomodate for the new adjusted hole size.
Also the Akront rims with the lip at the bead are the TR model which are very hard to find these days.
Sharpy, if you have a source for these, PLEASE BY ALL MEANS HELP ME OUT WITH A LINK, as I am really needing an Akront TR 2.50x18 WM4!!! I forgot about the GS1000 stock alloy rear rims looking similar. They are tough to find slso, however!

Thank you for the comparison photo for my purposes, here is what I have in the akront rims, and an old old NOS D.I.D. rim that has a slight lip on the edge unlike the newer the DID rims. The lip did not show up well with the lighting in the photo but can be seen at the bottom portion of the D.I.D. rim, it is bigger than it looks but still slight compared to both sizes in the Akront TR.




You are correct - the rear GS1000 2.50x18 alloy rim is a close match, I will expand my search.

Sorry for the hijack, Norm!! Thanks for dropping me that suggestion Sharpy!

[sharpy]

Opps spelling sucks. Sorry. Just rung my contact and seems TR Akronts haven't been made is ages. But we already know that. And there mid $500AU retail for a 4.25 X18 so we sure pay thru the nose. As for a rear rim on front. a redrill to suit 8 gauge spokes/ nipples isn't a hassle over here. Think we should stop. Im sure the original poster is getting confused LOL

[storm 64]

Haha, yes it does get confusing, but that's why I asked. In drag racing it was easy. Skinny tire on the front fat tire on the rear. I'm really just wanting spoke wheels for the looks, but if I'm going to do it I might as well do it right. Chuck is really making sence to me about the 18" front.... Hey Mr.Sharpy, I was wondering if you could draw me up a CAD drawing of a hole pattern for drilling GS brake rotors? You draw it I'll machine it��

[sharpy]

just the 6 bolt holes. or you talking the slots in the braking area? If its the slots maybe i can use this and mode it to suit the surface area of ure Discs.... https://grabcad.com/library/brake-di...satria-2-tak-1
but looking at them they look huge

[sharpy]

Great advice Chuck, I was hoping you'd chime in. I was getting ready to call you. I'm not not sure how the 18 inch front would look under my big chrome fender...

Below is how a 110 X 18 tyre looks on a 19in guard. Thats why i threw the GSX550 esd guard on. Only have to make cutouts for the brake hose brackets to fit.

[storm 64]

Baby got some brand new shoes

I got my wheels back from Woody's Wheel Works today. I think they look great and so much lighter! I kind of wish they didn't have the Excel logo on them, but it's good for now. I have to tape them up for tubeless tire application. I have the recommended 3M 4421n sealing tape so we'll see how that goes. I still have to drill my brake rotors, then everything should be ready for assembly ��

[Chuck78]

AWESOME!!!

Yeah we just learned how to use my new tire changer Saturday on a stock 77 gs750. I didn't say anything to my buddy who owns the bike, but wow the stock wheels and single disc rotors soooooooooo heavy!!! I had forgotten how heavy they are, I only have some without rotors mounted, and several sets of aftermarket aluminum rim GS wheels here...