Best rear tyre (size) for track.

Back in the days when the ‘steelie’ CBRs were raced in abundance, it was fairly common to see people fitting a 170 section rear tyre to the bike (like the SV they were meant for a 160 section as standard). Is this the case with minitwins?

Does it improve the handling/tyre choice*, or is it detrimental??

*I think tyre choice was the major factor in the steelie days.

I am probably taking my bike to the track soon and will need some ‘proper’/new tyres on there, so will have the choice of a 160 or 170, just wondering what is best for track use?

[northwind]

Officially, 160 is slightly pinched on a 4.5 rim (in practice, a lot of tyre manufacturers know that most of their 160s now go on 4.5s and so they make them narrower at the bead) 170 will likely be a wider tyre, and so slower turning, but also even more pinched and so might have a less than ideal profile.

I think only Avon recommend their 170 for a 4.5 rim.

The SV doesn't lay down enough power to need a 170 or 180 rear for traction while on track duty. So the 160 is the best size rear for the SV.

[NedSVS]

Blue_SV650S Wrote:

Back in the days when the ‘steelie’ CBRs were raced in abundance, it was fairly common to see people fitting a 170 section rear tyre to the bike (like the SV they were meant for a 160 section as standard). Is this the case with minitwins?

The older CBR's, FZR's & ZXR's were all on 5 inch rear rims, so a 170 wasn't pinched so much and good riders could use all that tyre. Avon actually say you can put their 170 on a 4.25 inch rim, but I personally wouldn't like to ride it. I beg to differ with northwind on the turn in speed issue. Larger sizes do have slower turn in on suitably wider rims, but the opposite when squeezed onto rims that are less wide than ideal; the reason being they get pinched to a more triangular shape and the trasition from running on the crown of the tyre to running on the side of it is more abrupt. This might not bother you too much if you are a very confident/compitent rider, but will quickly shatter your confidence if you aren't The main reason for the standard SV's flickability/fast turn in is because the standard tyre is slightly pinched. The tyre of choice for minitwins racing is the Supercorsa (usually SC1 compound front & SC2 rear), in standard 160/60 size. I've used these on the road in the summer months and at Cadwell for a track day - superb There are plenty of good used examples on Ebay once the mini twins season gets going properly, but the fronts will almost certainly be 120/70's. If you can scrub the rear to the edge, you should consider taking up Mini Twin racing

[northwind]

Originally Posted by NedSVS

I beg to differ with northwind on the turn in speed issue. Larger sizes do have slower turn in on suitably wider rims, but the opposite when squeezed onto rims that are less wide than ideal; the reason being they get pinched to a more triangular shape and the trasition from running on the crown of the tyre to running on the side of it is more abrupt.

Quite right actually. Though every tyre carcass design deforms differently.

There's also, possibly, a safety issue... Though this is more anecdotal than anything else.

[johnnyrod]

Nexus is right, this isn't a big or powerful bike, I've certainly had no trouble on track days using a 160 BT010, whether new or shagged (tried both, could have sworn tehre was more rubber left than that when I left the house...). Weather or size of nuts are usually the bigger deal. Mine are so big they drag on the ground, unliek my knee, doh!

depends on track, you might want to go smaller ... a 150 series for quicker turn in

Thanks for the replies guys, I’ll go for the 160 then. Anyone got any partworn supercosa’s??