SO2`s v MSPC (long)
11-06-2003, 10:33 AM
#1
Burning Brakes
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SO2`s v MSPC (long)
I`m stuck at home and have decided to write a comparison of my experience comparing road,- Bridgestone SO2 Pole Position and trackday, Michelin Pilot Sport Cups on my 964C2. Car is as described below:
AMD custom chip, Mass Air Flow kit and enlarged throttle body. Cat bypass, Blueflame custom silencers. Dyno`d at 298 bhp.
RS flywheel and clutch. 993RS 6spd gearbox.
H+R coilovers lowered approx 35mm
Carrera cups with 17 205/50 and 255/40 Bridgestone SO2 and RUF Speedlines with Michelin Pilot Sport Cups 17 225/45 and 255/40
993tt F calipers 965 discs 965 R callipers 951(RS) discs, Pagid yellow pads
Recaro SPG seats
Weight reduced by approx 75kg
On Track,
Tyre pressures; I run the MSPCS at 32psi hot and the SO2`s at 36psi hot
In the dry when hot the MSPC`s offer considerably more grip than the SO2`s with measurably shorter braking distances and clearly higher corner speeds than the SO2`s ( or the previous Pirelli PO`s) giving higher speeds on the straights. No great surprise as that is the remit of the MSPC.
Once hot the MSPC pressures remain constant within a small margin at 32psi and don`t need any further adjustment through out the day. ( I check pressures after each session). If I`m doing more than one day in a week or back to back week-ends I don’t alter the tyre pressures at home and find that after the first session on the new day they have reached working pressure (32psi). I find this pressure stability keeps the cars handling characteristics constant through out the day. When hot I find MSPC`s handling excellent, breakaway point is easy to judge and when passed the tyres just want to grip again, slides are progressive and I have always felt confidant that they were in control and grip would be resumed shortly, all of which allows driving right upto (and slightly beyond) the tyres max grip.
The problem with the SO2`s in the dry is that they tend to overheat; this leads to quite dramatic pressure increase in the tyres which changes their handling characteristics equally dramatically. Worse still is that the pressure increases are not equal tyre to tyre but increase more front to rear (braking ?) and outside ( of the track) to inside which does cause instability. SO2 tyre pressures can be difficult to equalise. The overheating of the SO2`s also causes the tyre to melt causing rubber to chunk of and decreasing the tyres grip – this also tends to occur in an unequal way tyre to tyre altering the cars handling. When overheated SO2 breakaway quite quickly and I find them difficult to recover from.
In the rain the SO2`s provide excellent grip and predictable handling. I`ve done trackdays in the rain where hardly anything has passed me all day on SO2`s ( sad to say more a reflection on the tyre). Moreover the tyre doesn`t overheat and pressures remain constant. The water probably acts as a coolant keeping temperatures and pressures down. SO2`s handling in the wet is more predictable than when hot in the dry with breakaway being gentle and recoverable (assuming I haven`t completely overdone it) The MSPC`s have insufficient tread pattern for water clearance and are hopeless in rain heavy enough to see splashes on the track, aquaplaning on braking, cornering, and acceleration. If its raining I won`t go out on MSPC`s.
No suprises in the above that MSPC`s are great in the dry and SO2`s in the rain, however both MSPC`s and SO2`s have problems with damp cold tracks; the SO2`s starting to overheat and the MSPC`s not, IMHO, reaching working temperatures. I don`t have a tyre pyrometer but using tyre pressures as a (approximate) guide to working temp`s I`m of the opinion they don`t reach optimum working temps in the damp; - they don`t feel as sticky to touch and the tyre pressures are 3-4psi less than I would expect in the dry. Moreover buttometer and speeds indicate noticeable performance drops and tyre breakaway is more sudden (MSPC). On balance I find if there`s water visible on the track SO2, a dry line MSPC.
On Road,
I have never driven as hard on the road as I do on track and it would be illegal and unsafe to do so, but even spirited (and illegal in the UK) driving in the dry doesn`t causes the SO2`s to overheat or pass their levels of grip by any worthwhile margin.
I have mixed feelings on the MSPC`s; in heavy rain I consider them of marginal safety with caution required. In the damp/cold they drive satisfactorily but my experience with them at the track always leaves me with doubts as to what would happen in an extreme/emergency manoeuvre. In the dry they have great grip when warm but the odd wheel spin early in journeys leads me to believe they do need to warm up whereas the SO2`s don’t. A 35-mile trip to the track will only raise pressures to 29-30psi if set at 32psi on a previous trackday indicating optimum-working temps is not reached on the road.
Wear,
The MSPC`s have done 5k miles 2k on track and are at the wear indicators, the SO2`s have done 6k miles 1k on track and still have more tread than the MSPC`s started with.
The ride and noise suppression is also worse with MSPC`s.
Of course YMMV
AMD custom chip, Mass Air Flow kit and enlarged throttle body. Cat bypass, Blueflame custom silencers. Dyno`d at 298 bhp.
RS flywheel and clutch. 993RS 6spd gearbox.
H+R coilovers lowered approx 35mm
Carrera cups with 17 205/50 and 255/40 Bridgestone SO2 and RUF Speedlines with Michelin Pilot Sport Cups 17 225/45 and 255/40
993tt F calipers 965 discs 965 R callipers 951(RS) discs, Pagid yellow pads
Recaro SPG seats
Weight reduced by approx 75kg
On Track,
Tyre pressures; I run the MSPCS at 32psi hot and the SO2`s at 36psi hot
In the dry when hot the MSPC`s offer considerably more grip than the SO2`s with measurably shorter braking distances and clearly higher corner speeds than the SO2`s ( or the previous Pirelli PO`s) giving higher speeds on the straights. No great surprise as that is the remit of the MSPC.
Once hot the MSPC pressures remain constant within a small margin at 32psi and don`t need any further adjustment through out the day. ( I check pressures after each session). If I`m doing more than one day in a week or back to back week-ends I don’t alter the tyre pressures at home and find that after the first session on the new day they have reached working pressure (32psi). I find this pressure stability keeps the cars handling characteristics constant through out the day. When hot I find MSPC`s handling excellent, breakaway point is easy to judge and when passed the tyres just want to grip again, slides are progressive and I have always felt confidant that they were in control and grip would be resumed shortly, all of which allows driving right upto (and slightly beyond) the tyres max grip.
The problem with the SO2`s in the dry is that they tend to overheat; this leads to quite dramatic pressure increase in the tyres which changes their handling characteristics equally dramatically. Worse still is that the pressure increases are not equal tyre to tyre but increase more front to rear (braking ?) and outside ( of the track) to inside which does cause instability. SO2 tyre pressures can be difficult to equalise. The overheating of the SO2`s also causes the tyre to melt causing rubber to chunk of and decreasing the tyres grip – this also tends to occur in an unequal way tyre to tyre altering the cars handling. When overheated SO2 breakaway quite quickly and I find them difficult to recover from.
In the rain the SO2`s provide excellent grip and predictable handling. I`ve done trackdays in the rain where hardly anything has passed me all day on SO2`s ( sad to say more a reflection on the tyre). Moreover the tyre doesn`t overheat and pressures remain constant. The water probably acts as a coolant keeping temperatures and pressures down. SO2`s handling in the wet is more predictable than when hot in the dry with breakaway being gentle and recoverable (assuming I haven`t completely overdone it) The MSPC`s have insufficient tread pattern for water clearance and are hopeless in rain heavy enough to see splashes on the track, aquaplaning on braking, cornering, and acceleration. If its raining I won`t go out on MSPC`s.
No suprises in the above that MSPC`s are great in the dry and SO2`s in the rain, however both MSPC`s and SO2`s have problems with damp cold tracks; the SO2`s starting to overheat and the MSPC`s not, IMHO, reaching working temperatures. I don`t have a tyre pyrometer but using tyre pressures as a (approximate) guide to working temp`s I`m of the opinion they don`t reach optimum working temps in the damp; - they don`t feel as sticky to touch and the tyre pressures are 3-4psi less than I would expect in the dry. Moreover buttometer and speeds indicate noticeable performance drops and tyre breakaway is more sudden (MSPC). On balance I find if there`s water visible on the track SO2, a dry line MSPC.
On Road,
I have never driven as hard on the road as I do on track and it would be illegal and unsafe to do so, but even spirited (and illegal in the UK) driving in the dry doesn`t causes the SO2`s to overheat or pass their levels of grip by any worthwhile margin.
I have mixed feelings on the MSPC`s; in heavy rain I consider them of marginal safety with caution required. In the damp/cold they drive satisfactorily but my experience with them at the track always leaves me with doubts as to what would happen in an extreme/emergency manoeuvre. In the dry they have great grip when warm but the odd wheel spin early in journeys leads me to believe they do need to warm up whereas the SO2`s don’t. A 35-mile trip to the track will only raise pressures to 29-30psi if set at 32psi on a previous trackday indicating optimum-working temps is not reached on the road.
Wear,
The MSPC`s have done 5k miles 2k on track and are at the wear indicators, the SO2`s have done 6k miles 1k on track and still have more tread than the MSPC`s started with.
The ride and noise suppression is also worse with MSPC`s.
Of course YMMV
11-06-2003, 11:16 AM
#2
Addict
Rennlist Member
Rennlist Member
Thanks for the info. I would agree with much of what you've observed and feel the stability of the MPSC's during track sessions make them a good choice for track work. Unlike the Kumho's, they do not get greasy on those hot days near the end of your session and last twice as long as the Victo's (from a $/mile perspective, they virtually cost the same).
As for the overheating issue with the S02's, I think that may be due to your low starting pressure. I recently ran my Pirelli PZeros at the track and found the optimal HOT pressure to be in the 44-46 psi range. Those numbers were confirmed with both seat-of-the-pants feel and pyrometer. Also, exit and top speeds were very near the numbers I produced with the MPSC's at the same circuit, so I believe the higher numbers were optimal for those particular street tires.
Your ending pressure of 36 psi suggests you may have started too low. I started the PZeros at 38 psi and consistently ended in the mid 40's without any of the traction or wear issues you experienced. With low pressures, there is considerably more flex in your tires and with all the heavy braking and hard cornering, the relatively soft sidewalls of the S02's may have exacerbated the heat issue.
I think the pyro is probably one of the best accessories for track day regulars, especially if you like to experiment with different compounds. The biggest upside is that you never "wonder" if you're running the right pressures which provides a great deal of confidence as you push the limits.
As for the overheating issue with the S02's, I think that may be due to your low starting pressure. I recently ran my Pirelli PZeros at the track and found the optimal HOT pressure to be in the 44-46 psi range. Those numbers were confirmed with both seat-of-the-pants feel and pyrometer. Also, exit and top speeds were very near the numbers I produced with the MPSC's at the same circuit, so I believe the higher numbers were optimal for those particular street tires.
Your ending pressure of 36 psi suggests you may have started too low. I started the PZeros at 38 psi and consistently ended in the mid 40's without any of the traction or wear issues you experienced. With low pressures, there is considerably more flex in your tires and with all the heavy braking and hard cornering, the relatively soft sidewalls of the S02's may have exacerbated the heat issue.
I think the pyro is probably one of the best accessories for track day regulars, especially if you like to experiment with different compounds. The biggest upside is that you never "wonder" if you're running the right pressures which provides a great deal of confidence as you push the limits.
11-06-2003, 04:16 PM
#3
Burning Brakes
Thread Starter
Join Date: Mar 2002
Location: WhippetWorld, .........is it really only this many
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Joey
As regards the So2`s, I run these at 36psi on the road which appears to be accepted as the correct pressure for these tyres, with no wear or handling problems. On arriving at the track I`ll just check the pressures are at approx these levels and are even then do a session, usually short and relatively gentle if open pit lane,and then recheck pressures. At this point the pressures have usually increased to over 40psi and , as above not equall increases on each tyre - but I`ll already know this because of the degradation in grip the tyres are offering. I`m not happy running the SO2`s over 40psi on track - were they are hot, or on the road were they are not.
Perhaps a tyre pyro could be on my Xmas list.
I had Pirelli PO`s prior to the SO2`s and IIRC they have a different tread pattern type with narrower channels. The tyre construction and compound will be different so pressure comparisons may not be valid. However I found your experience related in your thread difficult to reconcile with mine and the SO2`s.
I would be interested in a tyre that performs well in cold/damp conditions ( these are not uncommon here in the NW UK) as neither the MSPC`s or SO"`s are at their best in these conditions . Although a 3rd set of wheels may be seen as being a bit greedy
As regards the So2`s, I run these at 36psi on the road which appears to be accepted as the correct pressure for these tyres, with no wear or handling problems. On arriving at the track I`ll just check the pressures are at approx these levels and are even then do a session, usually short and relatively gentle if open pit lane,and then recheck pressures. At this point the pressures have usually increased to over 40psi and , as above not equall increases on each tyre - but I`ll already know this because of the degradation in grip the tyres are offering. I`m not happy running the SO2`s over 40psi on track - were they are hot, or on the road were they are not.
Perhaps a tyre pyro could be on my Xmas list.
I had Pirelli PO`s prior to the SO2`s and IIRC they have a different tread pattern type with narrower channels. The tyre construction and compound will be different so pressure comparisons may not be valid. However I found your experience related in your thread difficult to reconcile with mine and the SO2`s.
I would be interested in a tyre that performs well in cold/damp conditions ( these are not uncommon here in the NW UK) as neither the MSPC`s or SO"`s are at their best in these conditions . Although a 3rd set of wheels may be seen as being a bit greedy
