FZR Race Bike - current tire technology questions

[China_Racer_1]

Need a bit of advice here. I think I asked this question before but I never really got an answer I thought was exactly what I was looking for.

Ok Here is my issue.

I added a R-1 Front end on the 400 frame

So I got a fatter wheel up there.

I also added an f3 wheel in the rear which is a 5” wide wheel.

Question for racing on a twist track what is my best tire size. And please tell me why.

Right now I am thinking 120 on the front.

In the rear I am thinking either 160 or 170. I would rather a 170 but I am concerned if the profile will cup in. But would I even notice if I were on good DOT’s? I mean I plan to push the crap out of this bike. I built it to race it.

I just don’t want more tire for the sake of having more tire. I believe you can put to big a tire on a smaller bike.

However, I would rather go with a smaller 160 if that’s an issue.


Can anyone who may have ever owned a f-3 tell me what tires you have run and which worked butter under twisty race conditions? Even road back canyon racing - same thing to me, it pushes a tire hard as well for sure, anything like that for a comparison.

I tried to get 165’s. They said Michelin makes a set but I can not get them here.

I want them in a Pilot racer or pilot pro. I would rather the slicks but I found last race they were restricting us now to DOT tires if we wanted to have our place count in the race to be able to actually claim a prize…. No slicks form now on.

I don’t care either are great. I am sure brands differ on who is better but right now I want to keep the debate to tire size.

Keep in mind also that I have a basically stock 400 engine going in there right now. I will stuff a Built YZF 600 race engine in it

[China_Racer_1]

Bump

Anyone?

[FasterThanUr]

All I really know or have to say is a 170 will fit a 5" rim with no problems or cupping.The only benifit is if you couldent find a good sticky road tire in the 160 size.I never had a F3 but my old ZX6E had a five inch rim.If you want to do some reading on tires for that bike you can go to zx6e.net and theres a bunch of tire info on there,just search for tires/tire sizes...

[Xian_13]

....

Question for racing on a twist track what is my best tire size. And please tell me why.

Right now I am thinking 120 on the front.

In the rear I am thinking either 160 or 170.

I know you do understand the complexity of the question you are asking.
Lets start with basics...

The larger the tire, the greater the contact patch.
The larger the tire, the greater the weight.
The larger the tire, the harder the bike is to steer.

Now, lets break down the bike.
If you had a 110 on there and have gone to a 120, you are going to slow down the steering anyways.

Adding the 160 with the 120 will slow down the steering even more.
Putting on the 170... same thing, even slower streering.

Now to the steering effects on the 400.
If the geometry of bike is set up correctly, it should steer as well as a 250GP bike.
How can I say that? Because a 250 GP has that size wheel setup.
Yes, that is slower then a stock setup, but its more then enough to race.

Now take into account all the rotating mass you just added.
Now the bike is going to accelerate even slower...
However, in road racing, unlike drag racing, you don't go full throttle directly out of a turn.
In fact, you control the throttle based off of wheel spin.
So... the larger wheel will be harder to spin, so you will be able to use more throttle.

My advice is run the 170.
I know this, because I have a 180 on the rear of my Franken bike, which now has a bone stock 400 motor in it.

And for the record, on a local 2 mile course, I run 1:14.2s on a 115HP 600 and 1:19.5 on my Fizzer.
On the 600, I can make a rear tire last 40 laps if I stretch it out.
On the 400, the same tire will last about 75 laps.

XIII

[China_Racer_1]

Xian


Thanks I will go wiht a 120 front and a 170 rear. I needed to step up on the front only due to the R-1 front end I put on it.

Thanks for the advice.

Steve