crescentwrench Posted March 29, 2017 Share Posted March 29, 2017 Accidentally put a 120/60 up front instead of 70. Friend did the swap for free and it's on me for not checking the tires first. I am stuck with these for a little while at least, including for my second track day, Friday. How is running the lower profile tire going to affect riding? They're dunlop q3's and first pair of new shoes since buying the bike. I am taking it out this a.m. to test it out and break them in a tiny bit. I've been told it will mess up the geometry, and that it may be harder to turn in. I've also been told any loss in turning agility from the lower profile is going to be negated by the overall improvement from having significantly better tires. I'm worried because the rear end of the bike seems chattery or like high frequency bumps or bounces mid-turn some times when I'm leaned over. Seems like pitching forward could worsen that. Wanted to get alla y'all's thoughts and also to report my street and track findings in case anyone ever finds themselves in a similar situation or is curious. Link to comment Share on other sites More sharing options...
Premium Member pgeldz Posted March 29, 2017 Premium Member Share Posted March 29, 2017 Accidentally put a 155/60 up front instead of 70. Friend did the swap for free and it's on me for not checking the tires first. I am stuck with these for a little while at least, including for my second track day, Friday. How is running the lower profile tire going to affect riding? They're dunlop q3's and first pair of new shoes since buying the bike. I am taking it out this a.m. to test it out and break them in a tiny bit. I've been told it will mess up the geometry, and that it may be harder to turn in. I've also been told any loss in turning agility from the lower profile is going to be negated by the overall improvement from having significantly better tires. I'm worried because the rear end of the bike seems chattery or like high frequency bumps or bounces mid-turn some times when I'm leaned over. Seems like pitching forward could worsen that. Wanted to get alla y'all's thoughts and also to report my street and track findings in case anyone ever finds themselves in a similar situation or is curious. You meant you accidentally put a 120/60 on the front right? (not a 155/60) Because a 155/60 would really really not be the right size - Paulie Link to comment Share on other sites More sharing options...
Premium Member botticelli Posted March 29, 2017 Premium Member Share Posted March 29, 2017 Just send it! The suspension is the weak point on this bike, and the track will highlight that big time. As you noticed the rear has lots of chatter, this is due to the suspension not the front tire. Short of a suspension upgrade the chatter is here to stay. Good news is the track has much better pavement than the road, with no major mid corner bumps. If you the type of guy that is at the FZ's limits then yeah there may be some changes in the front end feel, but if not, and it sounds that way only being your 2nd time on the track, than take it easy for a few laps, get the feel and you will be just fine. Keep the rubber side down and happy riding. ~Pete '16 FZ07 Link to comment Share on other sites More sharing options...
crescentwrench Posted March 30, 2017 Author Share Posted March 30, 2017 Hah. Yes. I think it is 155 on the rear, right? Thanks also Pete. Good to know the chattering is a common issue. I took it up the twisties today and tires were AMAZING. I'm pushing it but not at limits yet. I think I was at my old tires' limits though...! I was sooo much smoother with the q3's today, lower profile be damned. I was not chattering where I was on Sunday w the old tires. Fx for track day. Thanks guys. Link to comment Share on other sites More sharing options...
gregjet Posted April 8, 2017 Share Posted April 8, 2017 If you have a 120/60 on the front instead of the 120/70 , it will in fact match the rear profile better. This will show up as you transition from and to upright AND at extreme lean. It will also lower the front by 12mm which is a LOT, but, IN MY OPINION, will assist the turn-in. I must point out that there are others with more pedigree that believe this is taking the trail even shorter and to a less than desirable amount, but my theory is that it helps mitigate the rear weight bias this bike has. NOW they may be very right on a high speed track as reducing the trail will lower the critical speed ( the speed where a rotational steering input into the front will not self damp), so treat my statement with due caution. A 120/60 is also lighter than a 70 so there are benefits with that as well. Suspension is the biggie. Stock suspension is aweful. Good suspension is the first step to useable speed. The Q3's are a stiff carcass tyre, plus the lower profile doesen't flex as much, so the final loaded effect on the tyre radius will be less anyway. All reports I have seen say it is a good tyre for this bike. I prefer more compliant carcass, but you can't argue with the Q3 grip. They are supposed to VERY stable sliding. The stock rear is 180/55 . I have strong opinions on the size of this tyre, especially on a track, but troll through the tyre and track threads for more information. Go forth and modify my son...go forth and modify... Link to comment Share on other sites More sharing options...
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