Rear Tyre Size

It's time for a new rear tyre, every time this comes around it seems all the names and available sizes have changed so a bit of advice would be helpful.

On the front I've got an AM20 Roadrunner 90/90 H19 on a WM2 rim which still has a lot of life in it.
Rear rim is an 18" WM3 currently fitted with an AM18 Super Venom 110/90 V18
The obvious thing to fit is an AM26 Roadrider 110/90 but there's also the option of the 110/80.

I've searched the forum and not found any comparison of the two sizes, anyone any views?

Rich

It might be worth asking Avon for the fitted dimensions of each type.

The 110/90 18 should be giving you a similar ride height to a 100/90 19. If you drop down to the 80% aspect ratio then you'll probably find the rear sitting a little low.

79x100 said:

It might be worth asking Avon for the fitted dimensions of each type.

Click to expand...

Roadrider tech. specs. http://www.avon-tyres.co.uk/motorcycle/roadrider


http://www.avon-tyres.co.uk/motorcycle

Mostly is a matter of how sensitive one is to handling ease and changing
worn out rear tires.

90x90x19 is as good as it gets for throttle and lean response but
wears out in 2000 miles if having much fun.
Almost any Cdo can grind-spin 90x90 in powered leans in 2nd.

The ~1" lower 110x80x18 will last longest and allow more
power in low leans in full grip than 90 to 100 profile but will feel a bit
heavy handed on throttle response.

Personally I find the more weight shifted to rear the better
it plants on pavement to Gravel. If not seeking tire traction
limits I'd say 110-x90x18 is the way to go for more level look
and 4000+ miles till cord shows.

hobot

Thanks for all the feedback, I went for the 110/90 in the end.

Trying to tame some handling woes so also getting the front wheel balanced and, if it can be done, get the wheels laser aligned.

Take it easy on new tires as mold release is a bugger till worn off careful.
Tires are a big deal to handling but getting the air pressures right
front and back make more difference than size or mixing bias and radial tires.

hobot

Take it easy on new tires as mold release is a bugger till worn off careful.

Click to expand...

Not sure if that was my problem but the AM26 I put on last year front and rear (90/90-19 and 110/90-18 were awful for the first 100 miles. Felt like the bike was going down at every turn (and I degreased them with thinners).
What size rim have you put your rear on Rich? Mine is on WM3 and it's too tight, really needs WM4. I get jokes about my 'chicken strips' but when I compare front and back I'd have to be over at 55 + degrees to use all the tread as the last 1/2 " is almost vertical. Front is on WM3 also and is a much better profile.

I'm on WM2 front and WM3 rear.

I've found the set up really sensitive to tyre pressure (as hobot mentioned), a few psi down on the rear and life starts getting interesting in a very bad way.

Changing rims is not really an option, I've wasted too much time and money already I need to keep it on the road now so just looking for small things that will settle things down a bit.

New tyre goes on tomorrow barring disasters at work, interested to see this laser alignment kit the tyre fitter has.
He wasn't too confident that he could get it to fit a classic so we'll see how it goes.

Anytime I get new tires on a bike I find an empty parking lot and do "figure 8's" (both ways and gradually leaning more and more) for a while. I have never successfully just wiped anything off of new tires.
Years ago the club was showing bikes at the big Auto-show in town, some Idiot came by and "shined up" my tires with some kind of Silicone-spray and when the show was over I rolled the bike off of the carpet and it slid out from under me. Talk about pissed! I had dropped the bike without getting on it and I could not pick the Commando up until I washed/cleaned the tires.

Unclviny

Unclviny said:

some Idiot came by and "shined up" my tires with some kind of Silicone-spray

Unclviny

Click to expand...

WTF?!?!??!!?

a) someone touched your bike without asking

and

b) slicked up the tires?

I hope you found out who it was and "shined them up".

Hmm, I laced Peel special with WM3 with hopes a 130 might fit,
so far 4 x on/off to find/fix spoke air leaks its not seated evenly
and may have to give up unless I can face re-spoke task again.

The worst time to test new tires in parking lot close quarter
or leaning turn to cross a road and turn into your lane BEWARE!.
Show slicked tire crash now that's a new one I hope to avoid.

Never ride into scary unsure states, ever, but on planned purpose
and places to creep up on leaning limits. Even un-rodded
Cdo can lean onto center stand or muffler or pegs when those
out the way. Its enough to remove the casting nubbins at
very edge of patch. I don't plan nor care if my factory
Combat is too scary to do that on, but I am planning on
tire spin on edges on Ms Peel, with power to keep it
loose way faster than prior, in a few planned places or tracks.

Any time the front is over powering the rear expect in
upright parking lot creeping, you are prone to going down.
Less air in front allows rear firmness to tell front what to
do. Then there's the springing of tire rebound front/back too.
I kept playing with low to high PSI and differences to get
best compromise.

I've not run a Commando yet on less than 110 tires at both
ends so don't know what I'm missing out on 100 on front yet.
This is past late great Ms Peel's 110-120 set.



hobot

swooshdave said:

I hope you found out who it was and "shined them up".

Click to expand...

I searched for them but they were either gone or not going to come forward, in the meantime I stopped the rest of the club from taking bikes off the carpet before scrubbing the tires. I'm with you, the motorcycle is the modern-day Horse and you simply DO NOT touch someone elses Horse EVER!

Unclviny