1975 850 Commando, hasn't been ridden in a long time, has original tires and I'm going to replace them and the tubes. Specs call for 4.10-19 (both front and rear), which I have found the metric equivalent to be 110/90/19. A friend says modern design/type tires offer increased stability, etc., rather than the vintage design, but when I contact supply places such as Motorcycle Superstore they indicate such current tires are directional and they only have the front, etc. It has been so long since I have even been on a bike I admit that I don't understand what they are saying. If it is the right size and direction for the front why can't it be mounted that way for the rear? Anyway, anyone who has information and advice for me will be greatly appreciated. Thank you.
Replacement Tires (2016)
- Thread starter mames
- Start date
- Status
- Joined
- Jan 27, 2008
- Messages
- 1,607
Tires are directional because the rear tire's main traction load is under acceleration and the front tire's main traction load is under braking. Tires such as the Dunlop TT100 4.10-19 (K81) and the Avon Roadrider (AM26) 100-19 have direction arrows for front or rear mounting.
If you've been quoted for a K81 or AM26, check the manufacturer data - these are both 'universal' fit tires.
When I first put my '73 on the road, I used the Dunlops. I switched to the Avons when those wore out, as the K81 tread design with the groove in the center of the tread liked to follow 'tar snakes' and seams on the asphalt, and riding over the grating on drawbridges was an adventure. The Avons have a modern tread pattern, and are much more stable on road irregularities.
If you've been quoted for a K81 or AM26, check the manufacturer data - these are both 'universal' fit tires.
When I first put my '73 on the road, I used the Dunlops. I switched to the Avons when those wore out, as the K81 tread design with the groove in the center of the tread liked to follow 'tar snakes' and seams on the asphalt, and riding over the grating on drawbridges was an adventure. The Avons have a modern tread pattern, and are much more stable on road irregularities.
Ron L
VIP MEMBER
- Joined
- Feb 27, 2004
- Messages
- 3,240
The Dunlop K81 and Avon RoadRiders are bias-ply tires. The tires are directional so the overlap of the plies are such that the braking force of the front tire and the acceleration force of the rear tire remain flat rather than try to roll up and separate. The tread pattern is designed to work in either front or rear orientation.
- Joined
- Jul 15, 2010
- Messages
- 637
Be aware that Avon does not recommend the 100/90 AM26 for the stock WM2 1.85" rims and if you mount one the profile will visibly be wrong due to the too narrow rim....that being said many have done it and lived to tell the tale.
FWIW have used them on a couple of bikes (not all Nortons) and like them a lot...and the universal versions do have have directional arrows that are opposite for front and rear mounting.
FWIW have used them on a couple of bikes (not all Nortons) and like them a lot...and the universal versions do have have directional arrows that are opposite for front and rear mounting.
I have Avon AM26 on my 1975 stock rims . They are universal and mount according to the direction indicator on the tyre .
My Norton handles as well as my 1999CBR 600F did . Would thoroughly recommend them . Make sure your tubes are in good condition , if there is any rust on them from the rims get new ones fitted .
My Norton handles as well as my 1999CBR 600F did . Would thoroughly recommend them . Make sure your tubes are in good condition , if there is any rust on them from the rims get new ones fitted .
lazyeye6
VIP MEMBER
- Joined
- Feb 28, 2014
- Messages
- 1,144
bluto said:Be aware that Avon does not recommend the 100/90 AM26 for the stock WM2 1.85" rims and if you mount one the profile will visibly be wrong due to the too narrow rim....that being said many have done it and lived to tell the tale.
FWIW have used them on a couple of bikes (not all Nortons) and like them a lot...and the universal versions do have have directional arrows that are opposite for front and rear mounting.
While Avon may not recommend the AM26 Roadrider's 100/90 use on WM2 rims (yes the ones your Norton came with),
Thousands of Commando riders are, in fact, using these tires on the stock WM2 rims and enjoying them very much.
They handle much better than the Dunlop T100. Also, it is best to use the 90/90 size on the front for even more responsive handling and conforming with Avon's rim size recommendations. I'm sure this could become an oil type thread with many diverse opinions, but am sure many folks more knowledgeable than I will support my opinion.
I run the AM26 on 3 Nortons and other than 1 flat tire due to a nail have never had a mishap over thousands of miles of often aggressive miles running through twisties.
- Joined
- Aug 8, 2005
- Messages
- 2,835
mames said:
mames,
I run the AM26 road riders and use the WM4 width rims, front and back. I am very pleased with the way these handle and couldn’t be happier. I use 100/90 both front and back on my 850. When the back tire wears out I switch the front to the back and place a new skin on the front. I use up a tire a year on average. It’s just a little more work but gives me an excuse to really clean my spokes and check my brake pads.
Cheers,
Thomas
CNN
Mr. Rick
VIP MEMBER
- Joined
- Feb 6, 2009
- Messages
- 793
I have the original WM2 rims, and use the Avon Roadrunner 90/90 front, the Avon Roadrider 100/90 in the back.
I've done no comparisons except with the old K81's, which were so bad (hard as a rock) that I could skid the front with a stock brake, and squirm all over on the grooved concrete with the rear. Tremendous improvement.
Glad to hear you're getting the old machine back on the road. Good Luck!
I've done no comparisons except with the old K81's, which were so bad (hard as a rock) that I could skid the front with a stock brake, and squirm all over on the grooved concrete with the rear. Tremendous improvement.
Glad to hear you're getting the old machine back on the road. Good Luck!
- Joined
- Dec 10, 2008
- Messages
- 7,253
I use the Avon Cobra AV71 front tire for both front and back on my bike. I mount the rear tire backwards from the directional arrow.
A little more expensive than the Roadrider but they are nice and sticky and I get nearly twice the mileage out of them. Jim
A little more expensive than the Roadrider but they are nice and sticky and I get nearly twice the mileage out of them. Jim
trident sam
VIP MEMBER
- Joined
- Oct 23, 2012
- Messages
- 1,468
comnoz said:
Jim,
In the UK I reckon if you were to reverse a tyre and have an accident for whatever reason , then the insurance company would dismiss your claim .
sam
Fast Eddie
VIP MEMBER
- Joined
- Oct 4, 2013
- Messages
- 21,596
trident sam said:
And the rozzer's would be all over you !
- Joined
- Aug 19, 2010
- Messages
- 1,967
Fast Eddie, that would be form over substance, typical bureaucratic conduct though, but then I'm just repeating your point. Well said.
Jim's onto something there.
Jim's onto something there.
lcrken
VIP MEMBER
- Joined
- Mar 15, 2009
- Messages
- 5,035
The tire manufacturers warn us not to run a "front" tire on the rear, even if we mount it in the reversed direction, but like Jim and many others, I've done it with no problems. Back when I was racing a Suzuki X6 Hustler, I had to do that to get any sort of decent race tires. I ran it around the high banks of Daytona that way, as well as a bunch of shorter tracks, with never a problem.
I've been running the Avon Roadriders on my street Commando, with 100/90-19 front and rear on stock WM-2 rims for over a decade now, also with no issues, except the universal does wear pretty fast on the rear. I like JIm's idea of AV71s, and might try that next time around.
Ken
I've been running the Avon Roadriders on my street Commando, with 100/90-19 front and rear on stock WM-2 rims for over a decade now, also with no issues, except the universal does wear pretty fast on the rear. I like JIm's idea of AV71s, and might try that next time around.
Ken
Thanks to everyone, I now know what I want to do. I am one of those people that should be "shot"--I've had cycle enthusiasts tell me so. I bought a brand new 1975 850 MKIII in December of 1976, put a little over 3,000 miles on it over the next year and a half and it has been sitting in a garage ever since. I was 24 then, I am 64 now. It's time, and I am looking forward to getting it back up in shape and enjoying this great bike--if I can remember how to ride 
MS850
VIP MEMBER
- Joined
- Jul 12, 2015
- Messages
- 493
Ive heard a few that have put on Metzeler Tourance, technicality they are dual sport, leaning more toward the road riding. Ive had them on my BMW GS and Vstrom, you can get a lot mileage out of them and I have ran them close to the chicken strips. They are great tires if you don't mine the aggressive pattern.
Avon AM 26 on stock rims here. No complaints at all!
In the past I ran Metzlers but I don't think the size is available anymore. The Avons are a very good handling and good value tire.
Don't forget to order new rim strips along with your new tires and tubes. I just fixed a flat on my daughter's boyfriend's bike and there was no rim strip - just a couple wraps of duct tape which failed, of course. All for a $3.00 piece of rubber.
In the past I ran Metzlers but I don't think the size is available anymore. The Avons are a very good handling and good value tire.
Don't forget to order new rim strips along with your new tires and tubes. I just fixed a flat on my daughter's boyfriend's bike and there was no rim strip - just a couple wraps of duct tape which failed, of course. All for a $3.00 piece of rubber.
mames said:Thanks to everyone, I now know what I want to do. I am one of those people that should be "shot"--I've had cycle enthusiasts tell me so. I bought a brand new 1975 850 MKIII in December of 1976, put a little over 3,000 miles on it over the next year and a half and it has been sitting in a garage ever since. I was 24 then, I am 64 now. It's time, and I am looking forward to getting it back up in shape and enjoying this great bike--if I can remember how to ride
I too bought my MK3 new and except for a couple of foray's with Avon Venom's I've stuck with Dunlop K81's. The Avons, while capable tires, never mounted circumferencely perfectly on the stock WM2 rims. I'm a bit gun shy to try Road Riders for the same reason. The old school Dunlop's stick fine and look right too. They mount up perfectly and remember, back in the day they were the cats nuts in the handling department, and a Commando is still a Commando.
- Status
