hi what is the biggest tyre you can fit on the rear wheel of a domi 99 using a stock swing arm and hub
Hi Robert. I can’t tell you what works, but I can at least suggest what doesn’t. When I bought my barn find 1960 Dommie 99 it had a 4.10 x 19 Avon on the rear. When I stripped the bike, it was clear that the tyre had been rubbing against the swing arm for a long time and had actually rubbed a couple of flat spots into the swing arm tubes. My guess would be that a 4.0 might work but I’m going to put a 3.5 in when I rebuild my bike.
The attachments may be of some help.
When the TT100 and Roadrunner 19 x 4.10" arrived they were both sold as direct replacements for the 19 x 3.50" Avon SM and K70 tyres widely being used. The TT100 was a bit of a squeeze especially if the rear wheel was well forward in the swinging arm. The US bound Nortons had 18 x 4.00" rear wheels/tyres on some models.
On my Atlas, in the 80s, I changed the rear wheel for an 18" size when 19" rear tyres became a bit scarce. This allowed me to fit an 18 x 4.25" Avon Roadrunner which gave excellent handling in all weathers. The equivalent size TT100 needed the side blocks shaving before it would fit.
My current 650 had an Avon AM21 18x100/90 on the rear which was really good. I am checking out what both Avon and Dunlop have to offer.
many thanks for the replies i would like to go with 18 on the rear and a 19 on the front so i think the avon 4.25 would be a good fit
I have 100/90 X 19 Roadrider on rear of my 1963 Dommie. With wheels in line there is a credit card thick gap at front left. With 18" it would, I imagine, have that bit more space owing to the splayed arms.
many thks david is that a wm3 rim ?
I have just fitted 100/90 X 19 Avon Roadriders front and rear to my 1959 wideline Dommie 99. Some people would say it looks non-original at the front because it is a fatter tyre, which it does, but the handling and smooth ride are well worth it. The snag is that the front mudguard has to be raised about 3/8" with spacers above the bracket, the bracket also needed minor squeezing where it is scalloped inwards, and I had to make new stays, a tiny bit longer. So, if that's too much hassle you could stick with an Avon Roadrunner front and just put the Roadrider on the back. It seems to fit OK with my original Norton rear guard. I reckon that handling matters more than appearance, and it is not an irreversible change.
Don't know off hand, Robert. It's standard as far as I remember.
I could not get the front 90x90 to fit the front. So I have a spare tyre taking up space...it might as well go on my Inter I imagine - but by the time that bike's tyre wears out they'll both be ten or more years old...
ok ill keep you posted on how i get on
Anything wider than a 3.50 SM will not fit my 99. My bike has the brackets for a fully enclosed chaincase. I also think the length of the rear chain has a bearing on this too. A long chain will put the wheel well back in the adjusters and allow more clearance at the case mounts. I expect it would be possible to fit a wider tyre if I would be ok with the back wheel to be well out of line!.Something else to consider, The Bikes gearing was calculated with the Deep walled SM tyre.A modern tyre my have a much lower profile and I have measured the O/A wheel height difference to be 2" in some cases. So you will be lowering the gearing and affecting the Speedo readings a bit.
That what you fit at the rear needs to complement that fitted at the front. Your bike being a 99 probably has 7" fork yokes which can cause issues with tyre to fork clearance. What you need to avoid is too big a difference between front and rear tyre width.
For what its worth I built up my 650 with 18" rims front and rear and run Metzeler ME33 and ME99's in 100/90x18 F 110/90x18 R. If I were to replace them I would go to the same tyres I use on my other bikes -Bridgestone BT45's as I simply don't like Avons.
many thanks for all the comments i have seen someone running a wm3 18" on the rear with a high wall tyre and a wm2 19"on the front i do want to replace with ali rims so next ill have a word with the wheel biulder see what he thhinks