|Posted on Thursday, March 25, 2010 - 12:59 pm: ||
I had an M2, and ran a D205 front with a 180 mm D205 rear (the M2 called for 170s), with no adverse effects. Not even noticeable.
On that same M2, I mixed the Dunlops with MeZ6's with only minor negative effects, though the bike turned smoother with proper matching (Metzlers or dunlops on both ends of the bike). Again, not a huge deal.
Well the Uly got a flat in the middle of nowhere, and Alex Prior (God bless him!) let me use an extra used D205 rear he had to get home. The bike had a new Scorpion Sync on the front. The tire Alex had was from his M2, so it was the proper M2 170mm, instead of the Uly 180mm. So it was the wrong tire, and the wrong size, and the wrong profile (the Dunlops feel triangular, the scorpions feel circular).
Oh what a mess it was. I could get home fine, and even rode the twisties OK, but it was clear there was something very wrong. The bike would go into a light wobble randomly going straight, and every time you started to tip into a corner. It would clear up, but it got tiring to try and ignore.
The lean was also a mess... it would resist turning, then flop over, at which point you would over correct to bring it back up... again, not much fun.
The size difference was very pronounced as well. When my M2 had the 180mm rear on the 170 spec rim, it wasn't that big a deal. Both front and rear (when matched) had about the same 5mm unused edge of the tire (chicken strips).
On the Uly with the 170mm rear, that back D205 was worn within 2mm of the edge, and that front Scorpion Sync had maybe 30mm untouched. So things were WAY wrong. No idea how much was a result of the profile, and how much was the result of the size, but both are clearly a bad idea.
So my guesses at conclusions (just that, don't read more into them)?
1) Get the right sized rear, but if you have to get the wrong one, go to a tire that is too big for the rim rather then too small.
2) Matched brands (or at least profiles) really do matter. I suspect a round profile tire like an MEZ6 might work OK with a round tire like a scorpion sync, but it did poorly with a triangular profile like the D205.
So there you go. I am now in the "don't mix tires, and don't use the wrong size" camp. Formerly, I was in the "mix carefully and know you are rolling the dice, but it will probably be OK" camp. I even thought seriously about putting a 170 series on the back of my 9sx to get a little faster turn in on that smaller motor... now I am glad I didn't have the nerve to try it.
So maybe this thread can be from the people that did have to mix and match and when it did work out OK. I can say that if the brands are the same (i.e. D205's or MEZ6's), tubers seem to work fine with 180's instead of 170's.
|Posted on Thursday, March 25, 2010 - 02:29 pm: ||
And Reep, I'm on the lookout for a nice used 180 rear to add to the Bueller Rescue Kit at the BRPMC, Jr. (Blue Ridge Parkway Motorcycle Club, Jr) just to make sure we're not messing up anyone's twisty riding capacity.
I should have ridden your bike a bit with that setup- now I want to do the math or model to show the difference...
Glad we learned and glad you got home!
|Posted on Saturday, June 12, 2010 - 05:57 am: ||
When I bought my XB9R it had the dunlop on the front and the scorpion sync on the back. I rode it like that for several thousand miles till the front needed replacing.
Yesterday I put a scorpion sync on the front. I literally would run off the inside of corners when I rode yesterday. I guess I got used to a certain amount of force to turn with the mixed tires and now the bike is turning quicker.
I would not have thought that mixing tires would have been that big of a deal.