Itty-bitty tires

Fluidlogic · August 8th, 2015, 01:32 PM

Hey, anybody have any success with altering tire size? I had a 190 on my CBR 600 and it was really nice having that little extra bit of rubber on the ground, and I think the contact patch size on the 250 is making me a little hesitant to really dig into turns.

Any thoughts? I know going too big on the rear can totally screw up handling characteristics, so what's the practical limit?

csmith12 · August 8th, 2015, 01:45 PM

A 140 in a type radial compound will give you the most contact patch + traction at the expense of mileage. Some 150's are known to fit but will change the patch size or tire profile.

Do NOT let the size of the tire prevent you from riding with confidence. Think about it... sumo's get stupid lean angle + speed with skinny tires.

cbinker · August 8th, 2015, 01:49 PM

lots of threads, try the search function.

Fluidlogic · August 8th, 2015, 01:50 PM

Quote:

Originally Posted by csmith12

A 140 in a type radial compound will give you the most contact patch. Some 150's are known to fit but will change the patch size or tire profile.

Do NOT let the size of the tire prevent you from riding with confidence. Think about it... sumo's get stupid lean angle + speed with skinny tires.

Yeah, I'm not too worried. It was just a "hmm... how far to push it" issue.

I'm still getting used to the maneuverability. I'll cheat off the seat for city street turns, and then realize that I don't even have to lean. It's weird.

jkv45 · August 8th, 2015, 01:52 PM

Search Google for Moto3 (250cc) cycles and look at the size tires they run - not very big.

Their cornering speeds are higher than MotoGP.

A bigger tire requires more lean angle for the same corner at the same speed - not an advantage.

Fluidlogic · August 8th, 2015, 01:54 PM

Quote:

Originally Posted by cbinker

lots of threads, try the search function.

Yeah, yeah, yeah, I know. Forum search functions always seem to return total messes, though. Hate wading through shredded bits of thread.

Fluidlogic · August 8th, 2015, 01:56 PM

Quote:

Originally Posted by jkv45

Search Google for Moto3 (250cc) cycles and look at the size tires they run - not very big.

Their cornering speeds are higher than MotoGP.

A bigger tire requires more lean angle for the same corner at the same speed - not an advantage.

Yeah, I saw a dude on a '15 300 smoke an R6 on streets at Willow. Wide open the whole time; never backed off.

Still getting used to the size of the bike. Thanks for all the feedback.

csmith12 · August 8th, 2015, 01:56 PM

Differences between a 600 and a 250.

cbinker · August 8th, 2015, 01:56 PM

Quote:

Originally Posted by jkv45

Search Google for Moto3 (250cc) cycles and look at the size tires they run - not very big.

Their cornering speeds are higher than MotoGP.

A bigger tire requires more lean angle for the same corner at the same speed - not an advantage.

ok how does that work? not to mention that the suspension, engine and weight are significantly different.

jkv45 · August 8th, 2015, 02:18 PM

Quote:

Originally Posted by cbinker

ok how does that work? not to mention that the suspension, engine and weight are significantly different.

Their lines are different for one thing, but other factors are also involved.

I'm looking for an article I saw recently comparing MotoGP lean angles and cornering speeds with Moto2 and Moto3, but no luck finding it so far.

Basically, IIRC, it was saying that MotoGP bikes need more lean angle in the same corner at a lower speed than the other bikes because of the larger tire, but I'll keep trying to find it.

Another thing about lean angle that you wouldn't expect - the lower the center of gravity the more angle is required.

Fluidlogic · August 9th, 2015, 12:57 PM

Quote:

Originally Posted by jkv45

Their lines are different for one thing, but other factors are also involved.

I'm looking for an article I saw recently comparing MotoGP lean angles and cornering speeds with Moto2 and Moto3, but no luck finding it so far.

Basically, IIRC, it was saying that MotoGP bikes need more lean angle in the same corner at a lower speed than the other bikes because of the larger tire, but I'll keep trying to find it.

Another thing about lean angle that you wouldn't expect - the lower the center of gravity the more angle is required.

Well, I have to say that the maneuverability of the bike has served me well in the most abjectly terrifying, blood-curdling, death-courting course ever:

Shopping mall parking lot on a Sunday afternoon.

August 8th, 2015, 01:32 PM	#1
Fluidlogic ninjette.org member Name: Michael Location: Newport Beach, CA Join Date: Aug 2015 Motorcycle(s): 2017 Ninja 300 Posts: 24	Itty-bitty tires Hey, anybody have any success with altering tire size? I had a 190 on my CBR 600 and it was really nice having that little extra bit of rubber on the ground, and I think the contact patch size on the 250 is making me a little hesitant to really dig into turns. Any thoughts? I know going too big on the rear can totally screw up handling characteristics, so what's the practical limit?

August 8th, 2015, 01:45 PM	#2
csmith12 The Corner Whisperer Name: Chris (aka Reactor) Location: Northern KY Join Date: May 2011 Motorcycle(s): 2010 250 (track), 1992 250, 2006 R6 (street/track), 2008 R6 (track) Posts: Too much. MOTY 2015, MOTM - Nov '12, Nov '13	A 140 in a type radial compound will give you the most contact patch + traction at the expense of mileage. Some 150's are known to fit but will change the patch size or tire profile. Do NOT let the size of the tire prevent you from riding with confidence. Think about it... sumo's get stupid lean angle + speed with skinny tires. __________________________________________________ Goal: Shake A Million Hands \| Look through the corners \| Track Day Prep \| Closest track? \| The Mid-Ohio School

August 8th, 2015, 01:49 PM	#3
cbinker Track Clown Name: Chris Location: Kingman, AZ Join Date: May 2012 Motorcycle(s): '08 250R, 21 MV F3 800, Kawasaki 400 build Posts: A lot. MOTM - Sep '15	lots of threads, try the search function. __________________________________________________ TEAM ALFALFA www.apexassassins.com

August 8th, 2015, 01:56 PM	#8
csmith12 The Corner Whisperer Name: Chris (aka Reactor) Location: Northern KY Join Date: May 2011 Motorcycle(s): 2010 250 (track), 1992 250, 2006 R6 (street/track), 2008 R6 (track) Posts: Too much. MOTY 2015, MOTM - Nov '12, Nov '13	Differences between a 600 and a 250. __________________________________________________ Goal: Shake A Million Hands \| Look through the corners \| Track Day Prep \| Closest track? \| The Mid-Ohio School

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August 8th, 2015, 01:52 PM	#5
jkv45 Rev Limiter Name: Jay Location: WI Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot. MOTM - Jun '18, Oct '16	Search Google for Moto3 (250cc) cycles and look at the size tires they run - not very big. Their cornering speeds are higher than MotoGP. A bigger tire requires more lean angle for the same corner at the same speed - not an advantage.