R Compound Choices on a 993 for DE
#16
There are 3 reasons why tire height, both absolute and differential are important
1) ABS function, the factory ABS is designed around an equal f/r tire height, it works best w/ no differential. There is some wiggle room but the further from nil the differential is, the more issues
2) fitment, the taller the tire the more restrictions are placed on chassis set up, things like alignment and ride height can be compromised
3) gearing effects, everyone has different needs here but a taller tires will have a lesser ability to accelerate the car at any given speed or rpm.
1) ABS function, the factory ABS is designed around an equal f/r tire height, it works best w/ no differential. There is some wiggle room but the further from nil the differential is, the more issues
2) fitment, the taller the tire the more restrictions are placed on chassis set up, things like alignment and ride height can be compromised
3) gearing effects, everyone has different needs here but a taller tires will have a lesser ability to accelerate the car at any given speed or rpm.
#19
Rennlist Member
Thread Starter
That's another issue not all of the tire makers have all the sizes we might wish for
MPSC
225/40 & 265/35 x18 is the base setup and works well, not the fastest and it has it's quirks but it lasts a long time
235/40 & 285/30 x18 is the 1st upgrade the issue here is that the front is taller than is desirable, yes it works but it's less than optimal
Hoosier R6
245/35 & 280/30 x18 perfect sizes great tire that just doesn't last as long as one could hope
Toyo RA1
the only 18" RA 1 is 275/35 x18
Nitto NT01
235/40 or 245/40 are tallish compared to 25" 225/40 x18
275/35 x18 is also tallish compared to 265/35 or 280/30 x18
Ventus Z214
245/35 x18 nice front size but 275/35 x18 is tallish for the rear
MPSC
225/40 & 265/35 x18 is the base setup and works well, not the fastest and it has it's quirks but it lasts a long time
235/40 & 285/30 x18 is the 1st upgrade the issue here is that the front is taller than is desirable, yes it works but it's less than optimal
Hoosier R6
245/35 & 280/30 x18 perfect sizes great tire that just doesn't last as long as one could hope
Toyo RA1
the only 18" RA 1 is 275/35 x18
Nitto NT01
235/40 or 245/40 are tallish compared to 25" 225/40 x18
275/35 x18 is also tallish compared to 265/35 or 280/30 x18
Ventus Z214
245/35 x18 nice front size but 275/35 x18 is tallish for the rear
Is there any problem with using a taller (bigger diameter) front? Based on spec I see:
Michelin 235/40-18 are 25.4", 285/30-18 is 25.2" and 295/30-18 are 25.2"
Nitto 235/40-18 and 275/35-18 are 25.6"
Hankook 245/35-18 is 24.7" and 245/40-18 is 25.6", 275/35-18 is 25.5"
888 255/35-18 and 295/30-18 are 25.1". Not sure I can get 255 on the front.
Comparing Hankook 275/35 and Hoosiers 295/30, diameters are 25.5" and 25.3"
I may give Hankkok 245/35 and 275/ 35 a try as they seem most similar to Hoosiers that I likely use for racing.
#20
Bill, Thanks for chiming in, as usual useful.
Is there any problem with using a taller (bigger diameter) front? Based on spec I see:
Michelin 235/40-18 are 25.4", 285/30-18 is 25.2" and 295/30-18 are 25.2"
Nitto 235/40-18 and 275/35-18 are 25.6"
Hankook 245/35-18 is 24.7" and 245/40-18 is 25.6", 275/35-18 is 25.5"
888 255/35-18 and 295/30-18 are 25.1". Not sure I can get 255 on the front.
Comparing Hankook 275/35 and Hoosiers 295/30, diameters are 25.5" and 25.3"
I may give Hankkok 245/35 and 275/ 35 a try as they seem most similar to Hoosiers that I likely use for racing.
Is there any problem with using a taller (bigger diameter) front? Based on spec I see:
Michelin 235/40-18 are 25.4", 285/30-18 is 25.2" and 295/30-18 are 25.2"
Nitto 235/40-18 and 275/35-18 are 25.6"
Hankook 245/35-18 is 24.7" and 245/40-18 is 25.6", 275/35-18 is 25.5"
888 255/35-18 and 295/30-18 are 25.1". Not sure I can get 255 on the front.
Comparing Hankook 275/35 and Hoosiers 295/30, diameters are 25.5" and 25.3"
I may give Hankkok 245/35 and 275/ 35 a try as they seem most similar to Hoosiers that I likely use for racing.
So far I've made the decision to stay w/ 225/40 & 265/35 MPSC, w/ 8.5" fronts(vs 8's) to help initial turn in. Tire heights difference is close to zero, Some cornering performance is being left on the table but to me the abs performance and durability are worth the compromise.
Friends use the 235/40 & 280/30 MPSC and and are very happy, If MPSC or some other brand were available in a durable tire ideally you would use 245/35 and 280/30 on 8.5 & 10, that is the setup that the 993Cups were optimized w/
All non stock size choices besides Hoosier 245/35 & 280/30 will involve some compromise
Hancook 245/40 & 275/35 are very close to equal height, so if they can be fitted in the wheel well and the gearing penalty is acceptable then that is a fair choice, 245/35 & 275/35 has a ~3% height difference and as long as the abs issue at that difference is acceptable then the gearing penalty and possible fitment issue in back are all that need tneed to be considered
#21
Bill, Have Michelin improved the 225/40 MSPC? I know when I was first using them on my '87 Carrera the 225's were quite a narrow 225. The 235's on my 964 are much better and give me great turn in and braking, then again, Dan Jacobs sets my car up for these tires only so I'm really running a great setup.
Cheers, James
Cheers, James
#22
Bill, Have Michelin improved the 225/40 MSPC? I know when I was first using them on my '87 Carrera the 225's were quite a narrow 225. The 235's on my 964 are much better and give me great turn in and braking, then again, Dan Jacobs sets my car up for these tires only so I'm really running a great setup.
Cheers, James
Cheers, James
here's a comparison, to get decent turn in I need to have Cup tie rods and the wider wheels, plus a decent alignment. But now they do work fine
Not mentioned previously is weight, just something else to muddy the water w/