Hey gang,

Just got some D404's put on the Fire Lizard based on what I've read here.  The rear tire is a bit beefier than the stock IRC, so I was wondering if I should harden up the rear suspension to allow for tire clearance underneath the fender.  The top of the tire is pretty close to some bolts back there (I'm guessing more so when I'm on the bike), and I was wondering if that was anything to worry about.  I'm 5'10" and 205 lbs.  Thanks.

Yes, You may end up ripping up your back tire if it drags along the bolts, which it most likely will. You can adjust the suspension but I don't know if it will really solve the problem. I have heard that you could consider grinding down the underside bolts to give more clearence or replace them with mushroom bolts. I'm in the same boat with mine (from the saddlebag additions that have rubbed against my 140/90-15, my suspension is already high and I'm only 5'6 130lbs) so I'll let you know if I find out any other good ideas.

I just had a Metzeler 140/90/15 put on the back of my bike at the local shop and the guys there seemed to think there was plenty of clearance. The shop where I bought the tire (not the same as the installer) was confident that moving up a size would be fine as well. My rear shocks are set on the hardest setting and I don't have any bags or other accessories mounted. I'm 5'8" 145lbs. I gotta say though, that when I reached under the fender to feel what kind of clearance there was, I was a bit concerned. If I put fingers between the bolts and the tire and really bounce hard on the seat I get pressure against my fingers, but not really a pinch. Hitting a bump at speed however may compress the shocks significantly more... So far I've done about 50 miles on the new tire and not noticed any trouble. I'd love to hear what others have experienced with a 140/90/15 instead of the 140/80.

The technical term is truss head or round head.  
Truss heads are lower in profile.

All dressed up for riding I weigh about 140 & the Dunlop shows no sign of contact with anything other than road.

OK, so here's my solution.  Went to Home Depot and bought some 5/16"x2" Hex bolts and removed the three stock bolts that were in the fairing.  With the new bolts in, it looks like I added an additional 1/8" of clearance, and now there's plenty of room...even for when the tire expands because of the heat.  It was a pain in the rear to put the bolts back in with rear tire still there (and I don't have a bike stand), but I got it done.  Oh, and I didn't put the third bolt back in, and the fairing still feels nice and tight.  Now, to figure out how to put on saddlebag supports.....

Do you mean bolting them on the outside of the fender, or cutting the tops of the supports off and JB welding them to the supports?

Take a look at this: http://www.hogantire.com/tctiresize.htm
As I understand tire sizes, a 140/90/15 should not be any wider than a 140/80/15. Both are 140mm wide. The /90 is 126mm tall (.9x140) while the /80 is 112mm tall (.8x140.)  The /90 is 14mm, just over 1/2 an inch, taller. 1in=25.4mm. Also, these are cross sectional numbers so the /90 will reduce the clearance under the fender by 14mm but raise the height of the rear end overall by 28mm unloaded. I would expect the taller tire may spread a bit more under load but I'd guess this could be compensated for with a bit more air pressure.