Topic: 550 Tire and Rim sizing

[bambuhiphop]

Hello All,

I am just about ready to order my new rims and tires for the bike. I wanted to just do a double check on my choices. I spec'd out this setup 2 years ago and I didn't take good notes on why I settled on this 

Anyway, I am dropping the front rim down to an 18" from a 19". Stock brakes. Stock Swing Arm. YSS Eco-Line shocks. 530 to 520 conversion. Engine will be putting out more than stock horsepower. Bike will be an around towner and weekend blaster.

Front: Buchanan Sun Rim -- RSWM218 SUN WM2 (1.85) x 18" with an AM26 Avon Road Rider 90/90-18
Rear: Buchanan Sun Rim -- RSWM318 SUN WM3 (2.15) x 18" with an AM26 Avon Road Rider 110/90-18

Any advice/help is appreciated!

[Lostboy Steve]

Do you have a certain look or handling characteristic that you want to achieve? I run a 110 90 19 and 110 90 18 on my bike and like the way it handles and looks. I'm on what I assume are stock steel DID rims.  We should really have a giant chart that shows what is recommended, reasonable, and completely unsafe.

[bambuhiphop]

Well I went with the 18 up front to help with turn in along with slightly lowering the front. My forks are slightly longer than stock so it won't be drastically lower up front.

Really the main characteristic I am looking for is quality cornering and tracking. I like the AM26 tires cause I think their profile balances classic and modern styles very well.

I found this chart in an old post: http://www.mtsac.edu/~cliff/storage/gs/Motorcycle_Rim_Width_Tire_Size_Chart.pdf#page=1&zoom=auto,63,732

[Gman]

Widths look right.  1.85" and 2.15"

[mono]

Do you have a certain look or handling characteristic that you want to achieve? I run a 110 90 19 and 110 90 18 on my bike and like the way it handles and looks. I'm on what I assume are stock steel DID rims.  We should really have a giant chart that shows what is recommended, reasonable, and completely unsafe.

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+1  i run avons in that size.  Its fine

[bambuhiphop]

So I decided to hop onto Avon's site and found the datasheet for the Road Rider line,

http://www.avon-tyres.co.uk/sites/default/files/product-specs/Roadrider%20pdf%20datasheet.pdf

It is a very nice chart with recommended rim sizes for all of their tires! How did I not find that before 

Anyway, the recommended size for a 90/90-18 is a 2.15 rim and for a 110/90-18 it is a 2.50

With that in mind I am thinking of upping the front from the 1.85 to a 2.15 and staying with the 90/90-18. Then on the rear I am thinking I will up to the 2.75 (no 2.5 available for the Sun Rims) and either stay with the 110/90-18 or possibly go with a 120/90-18...

I figure having a little extra rubber under there shouldn't hurt especially since I am upping the power of the bike. Something I wasn't originally going to do when I picked my setup.

My only question with running those slightly larger rims and tires is will I have enough clearance for everything??

[mono]

This has been addressed 100 times - you squeeze a wider tire on there and all you're doing is changing the geometry of the tire.  It will be out of round and change the contact patch and wear oddly, also affect handling.   But I'm not gonna preach.  People do it all the time, I just wouldn't myself. 

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[bambuhiphop]

That makes a lot of since Mono.

How much does rim width effect the handling and wear?

[Stev-o]

Read this thread before buying Avons, wish I had.


http://forums.sohc4.net/index.php?topic=123078.0

[mono]

I've had road riders on my 550 for 2 years almost and they're fine.  That thread seems to point to a lot of tires being mistreated.  Underinflation, etc.  But there are lots of other brands to go with too.

To answer your question about handling and wear from using an oversized tire, just think about it.   The more you squeeze the sides of a circle, the more elliptical it becomes.   

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[Lostboy Steve]

I've had road riders on my 550 for 2 years almost and they're fine.  That thread seems to point to a lot of tires being mistreated.  Underinflation, etc.  But there are lots of other brands to go with too.

To answer your question about handling and wear from using an oversized tire, just think about it.   The more you squeeze the sides of a circle, the more elliptical it becomes.   

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We're talking about one or two sizes (in width) over stock. I've been running them for 3500 miles through all types of terrain and road conditions. Wear is (visually) normal. I get down through turns even when hammering on the front brake. Bike sticks like its on rails.I think people who really have a problem with a slightly larger tire should try riding one and see how it feels. This isn't an educated guess, its been tested and proven. Its also good to be aware that the original sizes were based on 1970's era tires. Tires have come a long way in 40 years. Obviously you're 100% right in that running stock tires is RECOMMENDED and fail safe, and everyone is entitled to their opinions. I just don't want to discourage someone on an opinion alone.

[mono]

Yeah I'm not advocating it or saying it's dangerous, as I've never run oversized -- just that rims are made to run a certain size tire, and what you put on them is at your own risk.  I guess I just felt like someone should be the "mom" on this thread

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