315/30 MPSC
05-30-2008, 11:19 AM
#18
Rennlist Member
FYI here is the text from the Michelin Power Point Presentation on the MPSC:
• Another thing to remember: Bigger isn’t always better, both in terms of ease of driving and in terms of lap times.
• If you take a look at ALMS (prototype, GTS, or GT classes) tire/wheel combination, you will see that – even if the rules permit it – overly “fat” tires are rarely used.
• Bigger isn’t always better, both in terms of ease of driving and in terms of lap times.
• Frequently the tire looks “stretched out” on the application wheel, forming what looks to be a “trapezoidal” cross-section, with the tread width close to or less than the width of the tire’s beads. This is because of the simple fact that a “high-tension” tire shape is more efficient in most cases than a fat “low-tension” shape.
• If you are confronted with the choice of squeezing a big tire onto its minimum recommended wheel width or stretching a smaller tire onto a relatively wide rim, you might want to pause for thought.
• We have found the smaller-tire + wide-rim combination, with its accompanying “high tension” inflated shape, can be more efficient.
• More direct yaw response. Decreased “phase lag” between steering wheel input and vehicle turn it.
• Less “overshoot” at corner exit. Less of a tendency to “wiggle” at corner exit (thus upsetting the car) when you roll back onto the throttle.
• Can result in decreased negative camber requirements, thus increasing braking and acceleration efficiency.
• Can improve vehicle response to air pressure tuning
• Another thing to remember: Bigger isn’t always better, both in terms of ease of driving and in terms of lap times.
• If you take a look at ALMS (prototype, GTS, or GT classes) tire/wheel combination, you will see that – even if the rules permit it – overly “fat” tires are rarely used.
• Bigger isn’t always better, both in terms of ease of driving and in terms of lap times.
• Frequently the tire looks “stretched out” on the application wheel, forming what looks to be a “trapezoidal” cross-section, with the tread width close to or less than the width of the tire’s beads. This is because of the simple fact that a “high-tension” tire shape is more efficient in most cases than a fat “low-tension” shape.
• If you are confronted with the choice of squeezing a big tire onto its minimum recommended wheel width or stretching a smaller tire onto a relatively wide rim, you might want to pause for thought.
• We have found the smaller-tire + wide-rim combination, with its accompanying “high tension” inflated shape, can be more efficient.
• More direct yaw response. Decreased “phase lag” between steering wheel input and vehicle turn it.
• Less “overshoot” at corner exit. Less of a tendency to “wiggle” at corner exit (thus upsetting the car) when you roll back onto the throttle.
• Can result in decreased negative camber requirements, thus increasing braking and acceleration efficiency.
• Can improve vehicle response to air pressure tuning
05-30-2008, 12:09 PM
#20
Three Wheelin'
I've just switched from running Toyo 888s for 2 years to MPSCs in standard sizes (235/295 F/R) and they are night and day better. The tyres are more incisive, don't overheat nearly as quickly, offer more grip, are more comfortable on the road and don't make a hideous droning noise at 70mph.
I won't be going back to Toyos unless its for cold winter/rain (without standing water).
Having also changed my suspension to intrax 4 ways initially on the toyos, the cups are without doubt the final piece of the puzzle. The car feels amazing now - so neutral + forgiving but without roll and still able to take kerbs.
In hindsight I'd suggest that 888s don't really suit the 911.
I won't be going back to Toyos unless its for cold winter/rain (without standing water).
Having also changed my suspension to intrax 4 ways initially on the toyos, the cups are without doubt the final piece of the puzzle. The car feels amazing now - so neutral + forgiving but without roll and still able to take kerbs.
In hindsight I'd suggest that 888s don't really suit the 911.
05-30-2008, 02:15 PM
#21
Rennlist Member
Michelin also has regrooving instruction for using the cup tires in wet weather. You can download their brochure at http://www.tirerack.com/tires-techpage-1/62.shtml
Page 7 explains the patterns. I haven't tried it so no comments as to whether it works or not.
Page 7 explains the patterns. I haven't tried it so no comments as to whether it works or not.
05-30-2008, 04:13 PM
#22
Marcin,
It does not work with 11" wheels. Many people have tried it here and all corded the tire on the edge in 30% of their usual tire life. The tire will fit and it will not rub, but it will roll over in a hard corner and the contact patch will be very small. In a straight line or drag race the 315 MPSC would be fine. Stop modifying and drive. Learn the car you have.
It does not work with 11" wheels. Many people have tried it here and all corded the tire on the edge in 30% of their usual tire life. The tire will fit and it will not rub, but it will roll over in a hard corner and the contact patch will be very small. In a straight line or drag race the 315 MPSC would be fine. Stop modifying and drive. Learn the car you have.
05-30-2008, 06:25 PM
#27
Rennlist Member
Ah, I see your perspective. It's why I almost went for 7.5 width rims on my WRX instead of 8s. It would fit better I said to myself, don't want to push things... However, I went with 8s, rolled the rear fenders and everything fits fine. I'm very happy with it and I think the performance and feel is better because of it. So my point is just that I've spoken in person to someone who runs 12s with almost no issue (I think he said there is one place where he "thinks" he hears a rub on the fender, but a roll would fix this). 12 is better than 11 so if it was my car, I'd do it along with 9 or 9.5 fronts.
05-30-2008, 06:28 PM
#28
Rennlist Member
05-30-2008, 06:37 PM
#29
Nordschleife Master
Ah, I see your perspective. It's why I almost went for 7.5 width rims on my WRX instead of 8s. It would fit better I said to myself, don't want to push things... However, I went with 8s, rolled the rear fenders and everything fits fine. I'm very happy with it and I think the performance and feel is better because of it. So my point is just that I've spoken in person to someone who runs 12s with almost no issue (I think he said there is one place where he "thinks" he hears a rub on the fender, but a roll would fix this). 12 is better than 11 so if it was my car, I'd do it along with 9 or 9.5 fronts.
It's not so much the width that will affect the new final drive as it is the diameter. If you stick with cups, stick with 295's. If you want to head outside that playground, then there are many options to try out until you find what you like.
05-30-2008, 06:53 PM
#30
Rennlist Member
What does "almost" no issue mean? Further, why would you want to run a 12" wheel back there? It is not a proper fit. You would be adding weight which is the last thing you want on these cars, plus you have to run an uber wide tire (more weight) which has no benefit. I'm just confused why some feel bigger is better when it comes to tires.
I do that all the time.
It's not so much the width that will affect the new final drive as it is the diameter. If you stick with cups, stick with 295's. If you want to head outside that playground, then there are many options to try out until you find what you like.
I do that all the time.
It's not so much the width that will affect the new final drive as it is the diameter. If you stick with cups, stick with 295's. If you want to head outside that playground, then there are many options to try out until you find what you like.
I am going to put in the r&p and see what it is like with the stock sizes... if okay, then I am man enough to leave well enough alone
if I need more... Roberga is my local contact running the big R6 meats
