Hi All...in a recent shed rummage I came across an unused 4.00 x 19 tyre I had forgotten I had! Just wondered if this would fit my M20 with a view to putting a bit more air and rubber between the potholes and my aging bad back ! Anyone tried this before ? It looks to me as if there will be just enough clearance but wondered if anyone had tried it before and encountered any problems ?? May Thanks .Andy B

Hi Andy, I run 400x19 mitas tyres on my wm20 front and rear with no problems at all, Regards John.

email (option): rustytmm20@hotmail.com

when I got my wdm20 still in it post war colours the rear was a 1954 dated wd marked tyre 400 tyre so that's what went back on to her

email (option): karl.edmondson@btopenworld.com

I tried to help someone in Normandy who was running a 400x19 in the rear of an M20, he broke his rear chain quite a long way from the camp site, he had a new spare chain with him but neither of us had a half link, and because the tyre was so big there wasn't enough room to move the wheel forward or back to get any sort of tension.

I'm not saying you shouldn't but in his case it did make life more difficult.

Rob

email (option): robmiller11(a)yahoo.co.uk

I fitted a 400 x19 Avon block tread tyre to my WM20 rear wheel and as Rob said you cant slide wheel forward as the oversize tyre hits the mudguard where it is crimped in to clear the chainguard so have gone back to 350 x 19 size.I use 100/90/19 tyre on the front wheel with no problems though... Dave

I fitted an Avon SM Mk2 tyre to the rear of my M20 some time ago and found that the fore and aft movement was restricted and with my tired rear stand there was insufficient room between the rear of the main mudguard and the cross bar of the stand to remove/replace the wheel without deflating the tyre! As it was new it would be at its greatest diameter which also raised the gear just a tad too much for some riding conditions. If you ride fast (sic) there might also be problems with tyre growth from centrifugal force. Other makes or part worn tyres may very well be fine but it didn't work for me.
Richard

Thanks for the input......
I suppose if it it ain't broke don't fix it!!
As the current tyre is ok I will leave it for time being.
May be have a play with it when its not essential to keep bike on the road!
Many Thanks for the comments.

Andy B.

I thought Ian might have pitched in. I remember he had 400x19's at one point. But I think he said it affected the handling to some degree and was a bugger to remove/fit the rear wheel as he had to let the air out to get it past the top of the mudguard. He then reverted to 350's. Ron

email (option): ronpier@talk21.com

Yes...I used 400 Dunlop SM tyres...With these fitted I did have to deflate the tyre to remove the wheel as Ron recollects...There was also a clearance issue with the cross bar on the rear stand...

The SMs have a 100% aspect ratio I believe (the height of the sidewall in relation to the tyres width) and that was a factor in that case...

I fitted one on the front as well and though I liked the 'chunky' look of the tyres I thought they made the bike handle like a barge with heavy steering...

At the end of the day I suppose it's down to what you like the look of and what you feel comfortable with on your bike...Tyre performance is a very subjective thing after all...

I reverted to my usual 350 x 19 Dunlop K70s at both ends to eliminate the clearance problems and to restore the more 'nimble' handling...which is a relative term on the M20... ...Ian

email (option): ian@wright52.plus.com

That'll be Avon SMs (safety mileage)..not Dunlop...Ian

email (option): ian@wright52.plus.com