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Mar 21, 2006
I'd like to replace the tires on my '75 Norton 850 Commando, and I believe (and I'm not sure about where I heard this) that the max tire width is 100 mm X .90 section height.

Id there a somewhat "meatier" tire available that would still clear the rear swing arm?

What I'm really looking for is a source that any of the forum members have used for tires.

I'd like to get a "V" rated tire for the occasion where I might attempt the land speed record for Norton's in Phoenix....

Thank you.

Not Swingarm - CHAINGUARD... That's the sticky wicket.. I had a 130 on Midnite, clearing the swing arm, but could not fit the chainguard unless I was willing to shave rubber off the tire.. A 110/90 JUST clears everything.. and from the looks of it, a 120 wouldn't make it either...
I have a 120/90-18 on the rear of my cafe racer. It required cutting about a 1 inch notch in the chainguard to assure tire clearance. It also slowed the turn-in. I think I'll try a 110/90-18 Avon AM21 Roadrunner next.
74 Commando, Metzler Lazertec 120/90 - 18, Akront 2.15. NO alterations to chain guard.
Tires or Tyres

Is that a verb or a noun ? 'cos my tyres are getting tired too.


Commando - Brian (Magic Roundabout!)
Trident - Ermintrude (ditto)
Wife - Kaz
& Two teenage daughters ( £££$$$$)
to elaborate

Why the need for a great big chunky back tyre? George Shuttleworth - TT legend, managed a lap time still to be beaten on nothing more than bicycle wheels. Trouble is that a 19" rear rim limits the availability of decent rubber. Hmm! 18" rim?

For my money, and I havn't even fitted tyres to my beast yet. I would be trying Avon super venoms, same skin front & rear. They make a 100-90 x 19 that is front & rear fit. Handling should be at about optimum.

Regards Richard

For my money, and I havn't even fitted tyres to my beast yet. I would be trying Avon super venoms, same skin front & rear. They make a 100-90 x 19 that is front & rear fit. Handling should be at about optimum.

Regards Richard
Hi Richard,
I found that Super Venoms worked well on my triple, but using an 18" rear rim (100/90v19 and 110/90v18). Tho' the TT100's seem OK on the Commando.

I haven't tried every tire combo, but I have tried several including 18's.
The 100 / 90 X 19 Avon Super Venoms work very well on an 850.
The insecure thoughts of the 'skinny' rear quickly vanish once you start rolling it from side to side.
I had the popular AM20/AM21 combo (19F, 18R) for several years until the last rear replacement and went for an AM18 Venom. It has a noticeable curvature (smaller radius?) compared to AM21 and really tips on it's side quickly. However it also wears fast and soon gets to the square edge stage where handling gets nervous. The front AM20 is now worn out as well as the AM18 and I was thinking BT45's for a change. Has anyone tried them on a Commando?
Tyres revisited

I, too, run Avon AM20 90x90x19 front and Super Venom AM18 100x90x19 rear. I find the grip from the Super Venoms to be totally satisfactory. The tyre runs warm all the time and sticks really well. It does wear quicklt as a result and its round profile flattens off causing some loss of footprint when initially rolling into a bend. I don't suppose there is a way around that one. To get grip you need soft hot running compound but wear rate is bound to be higher.
I am not as happy with the narrower front AM20. Whilst it runs warm it does not seem to me to be quite grippy enough when surfaces become dusty or loose. The bike turns quickly and response is very good but I think I would settle for AM18 front and rear, both the same size. It might make the turning a little duller but might also suit the Commando better and make it less nervous.
I read on some other forum (damned if I can remember which one) that the Bridgestone MT35 (now superceded to MT45) were the best that this chap had tried, Avons included. So, like Keith, I was hoping someone on our forum might have views on this.
I also have 100/90x19 Supervenon rear and 90/90x19 Roadrunner front and agree with Scim77. The narrow front isn't to my liking. I just put a un-mounted 100/90x19 under the front fender and it doesn't clear at the sides. This is on a '72 750 Commando that has the narrow chrome plated fender as compared to the stainless from '73 onward. Anyone get the larger tire to fit the early setup? I may go back to original 4.10 x 19 front and rear although the supervenon sticks nicely.
75 MK3 here with 100/90X19 rear and 90/90/19 front, Avon Super Venoms. The modern tread profile doesn't go with the antique lines of the bike but the tires work so well I'm willing to put up with a bit of eye-sore.
Just got 950 miles on BT45 I talked about earlier. They are a revelation when it comes to UK tar banded mile after mile of under road cabling/gas/water repairs. These just don't track as badly as the Avons. Can't get a 90 for front but 100 and 110 work and they grip well. Yes you lose that quick 90 section turnin but I can live with that or buy a sports bike.
Hi Doc


All i have ever used is TT100's and while i thought that they were giving me the best to be expected i have just realized this year that a good tight swing arm , properly set isolastics and progressive springs in the front really made the difference. You can put whatever tire on you want but the rest of the bike needs to be set up correctly for any positive affects
Hi Keith1069. When you say that Bridgestone BT45 dont track as badly as Avons do you mean that they are less prone to wandering off line when road surface edges are inconsistent due to repairs, cambers, white lines etc? Do you find the BT45 run as warm as Super Venoms? Is the overall grip as good as Super Venoms? Do you feel more confident under most conditions? I dont suppose you have had chance to try them in wet conditions, not that we like using the bikes in the rain. Cheers.
Hi, Scim77
That's right, couldn't think of the word but I meant tramlining. Even with new Avons and no squaring-off on the rear they always uncannily followed the edges of road repairs, similar to cars on the inside lane of a worn motorway, in the grooves made by heavy trucks. The same goes for white lines and I haven't changed anything else, wheel alignment etc. Grip is good but I've not been out in much rain and when I did they only had a handful of miles on them. Have not measured the temperature! but the rear does not get seriously warm. The tread pattern is not as sporty as Avons and has deeper and more grooves. Subjectively, the compound feels softer than the Avons. I didn't believe the way they ran on repairs & white lines at first until I deliberately tried to follow them but they really are that forgiving. Time will tell when the rear starts to wear. Hope this helps.
I use Bridgestone's Spitfire 11 F's. A 100/90-19 front and a 110/90-18 rear.
They are dual compound feel real good on any surface. Iam going to a 100/90-18 for the back now that I am over fat for the back syndrome. You don't want to try hand mounting these. At least double the work. I don't think that there is a rear tire that I can't peel flat in one year. No I don't use the rear brake much (rear sets).
Just an update on the BT45's I fitted mid May. Now have 1500 miles on them and they are exceptional, IMO. Went off to a bike day in a little market town 60 miles away on Saturday and after 10 days of heatwave (up to 96F) the weather changed and 2" fell in an hour or so. Rode back through water up to the front disc, feet in the air, but had to shelter with others in a gas station for 1/2 hr. After the rain eased and the 'river' subsided we took off and the feel from these tyres is difficult to describe. I had more confidence than ever had with Avons, they just felt so secure on wet greasy tarmac. Ok, so I took it easy on our Diesel covered roundabouts but they feel amazing. Pity they're Japanese!
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