Lets talk Tire Pressure...

[IdahoRenegade]

I went Darkside a couple weeks ago with a BFGoodrich g-Force Sport COMP-2, size 225/55-16, on a '12 Roadster. Honestly...didn't care for it. Very noticeable tendency to "push" to the downhill side of crowned roads and pretty uncomfortable on uneven road surfaces. Some roads in my area get a lot of studded tire use during the winter time, which results in noticeable ruts. These were very apparent and disconcerting. Wasn't sure I wanted to put up with this to save downtime with tire swaps and money. Got about 1000 miles and was getting used to it, but not enjoying it.

Well...I have a confession. I had been running 33-34 PSI (and about 36 front). Seemed like I read about those values somewhere. Last night I dropped the rear to ~31, pumped the front up to 38 (due for imminent replacement anyway). Rode to work today (50 miles) and the bike is just transformed. That tendency to go "downhill" on crowned roads is pretty much eliminated! Can't believe the difference, and have trouble telling the difference between this and the old Metzler. I need to play some more and really find the sweet spot. Which I should have known by reading other comments, but I hadn't followed through properly.

Anyway, the difference was so great, I figured it was worth a separate thread just to talk about tire pressures. It's mentioned in some of the tire selection threads, but not as...prominently as it might be. I'm curious, what are others running, and what are signs when you are either side of the "sweet spot"? Thanks.

 

[JRock]

I run 28 psi.
Be brave and try it.

 

[rocketjohn]

Yep one of the things about making a darkside set up feel right is finding the pressure that works for you. Given the weight a car tire was meant to take and at the pressure stated on the tire, it's pretty certain that carrying half that weight means a lower pressure....but WHICH pressure, is a matter of trial and error. And if you change to a different model of tire, you'll have to do it again, but at least you'll know about where to start.

 

[Chris Kelley]

I run 28 psi.
Be brave and try it.

Pretty sure that'she where most of the older Sith Lords recommend you start.

 

[Wannbe]

If your front needs replacing try the 140 tire. The smaller front completely changes the handling and pushing for the better. I was ready to go back to mc tire before changing the front.

 

[rocketjohn]

What aspect ratio should the 140 be? Does it come in a tubeless radial Avon cobra?

 

[Wannbe]

Got this from someone else here, I have found it useful many times.

 

[IdahoRenegade]

If your front needs replacing try the 140 tire. The smaller front completely changes the handling and pushing for the better. I was ready to go back to mc tire before changing the front.

I'm just a little too late-have a 150 Cobra sitting in the shop ready to go on. Next time, and thanks for the tip.

 

[1olbull]

Got this from someone else here, I have found it useful many times.

Thank you for the compliments!

 

[IdahoRenegade]

My Darkside education is continuing. I dropped the pressure to 29 a couple days ago, which made a slight improvement. Still a bit "squirrely" on uneven, slightly rutted dirt roads, and still a little tendency to push down hill on crowns. And a little bit of transition when leaning into corners. But very manageable, I was quite satisfied.

Today I put a new FRONT tire on (Avon Cobra in 150) and took it for a ride. What a change! All the quirky handling seemed to vanish. I went and played on my favorite tight twisty road, it sucked it up at least as well as with the stock MC tires. It actually felt much more planted and the transition from left to right hand curves was smooth with none of the "thump" across the flat of the tire I had noticed (exaggerated a bit but the feeling was there). Even more pronounced was the feeling on my gravel road. All the bad feelings on ruts/ridges was gone. Felt much more planted than stock, now it feels good enough to push in to corners. The stock street tire with it's minimal tread always wanted to wash out in "marbles". The extra grooves in the CT almost seem to act like knobbies on an ADV bike. Feels so good that I was getting carried away and "roosting" a bit, just like the Tiger.

I don't really understand why a different front tire made such a difference, but in my case it did. I wish I had tried the 140 tire that Wannbe suggested. I suspect the CT is a little bit smaller in OD than the stocker, which lowers the rear and has the effect of increasing rake. The smaller front might counter that and "quicken up" the steering, with less need to countersteer. I understand the Bridgestone 55 series MC tire was supposed to have that effect compared to the 50 series Metz.

OK, enough hot air, as of now I'm a committed Darksider.