what is the OPTIMAL tire size w/ 19" wheels
#1
01-02-2007, 10:06 PM
what is the OPTIMAL tire size w/ 19" wheels
i notice most of you guys have 235's up front and 315s in rear
i was just curious why i dont see more people going for a bigger size up front, maybe a 255 or 265 ?
im sure you can find a proper size, thats wider and keeps the same rotating diamter as the rears ...
i was just curious why i dont see more people going for a bigger size up front, maybe a 255 or 265 ?
im sure you can find a proper size, thats wider and keeps the same rotating diamter as the rears ...
#2
01-02-2007, 10:20 PM
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#3
01-02-2007, 10:22 PM
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315/25/19s on a 12x19 rim
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2001 996TT 3.6L and stock ECU
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2001 996TT 3.6L and stock ECU
9.66 seconds @ 147.76 mph 1/4 mile click to view
160 mph @ 9.77 seconds in 1/4 mile click to view
50% OFF ON PORSCHE ECU TUNING BLACK FRIDAY SPECIAL
#6
01-02-2007, 11:58 PM
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Originally Posted by cpu77
What wheels are those?
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2001 996TT 3.6L and stock ECU
9.66 seconds @ 147.76 mph 1/4 mile click to view
160 mph @ 9.77 seconds in 1/4 mile click to view
50% OFF ON PORSCHE ECU TUNING BLACK FRIDAY SPECIAL
2001 996TT 3.6L and stock ECU
9.66 seconds @ 147.76 mph 1/4 mile click to view
160 mph @ 9.77 seconds in 1/4 mile click to view
50% OFF ON PORSCHE ECU TUNING BLACK FRIDAY SPECIAL
#7
01-03-2007, 12:00 AM
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#8
01-05-2007, 11:10 PM
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If you want to increase turn in/turn out grip (i.e. reduce understeer), would it make sense to start by making sure that your rear track is not too wide, and then work on front camber ? More rubber is not always the best solution.
#9
01-05-2007, 11:35 PM
Originally Posted by ze_shark
If you want to increase turn in/turn out grip (i.e. reduce understeer), would it make sense to start by making sure that your rear track is not too wide, and then work on front camber ? More rubber is not always the best solution.
What occurs: Push, plowing, front tires slide out first.
Opinion: Usually slight understeer is safer.
Tips to Correct (hint: change one thing at a time and test)
Raise front tire pressure.
Raise front tire pressure.
Lower rear tire pressure.
Soften front shocks. Stiffen Bump.
Stiffen rear shocks.
Lower front end.
Raise rear end.
Widen front track.
Install shorter front tires.
Install taller rear tires.
Install wider front tires.
Install narrower rear tires.
Soften front sway bar.
Stiffen rear sway bar.
More front toe out.
Reduce rear toe in slightly.
Increase front negative camber.
Increase positive caster.
Soften front springs.
Stiffen rear springs.
May need more front suspension travel.
Install wider front wheels.
Use softer front compound if possible.
Use harder rear compound if possible.
Remove weight from front of vehicle.
Add weight to rear of vehicle.
Drive a different line.
Use weight transfer to your advantage.
High Speed. Increase front wing downforce.
Too much front brake.
Vehicle is TWITCHY at limit and hard to keep
ahead of in the steering department.
Lower front and rear tire pressures slightly.
Suspension may be too stiff.
Shocks may be set too firm.
Tires may be old or hard.
Vehicle may not have enough suspension travel.
Vehicle may have a toe problem front or rear.
Increase negative camber front and rear if possible.
Last edited by cjv; 01-06-2007 at 12:07 AM.
#10
01-05-2007, 11:38 PM
Originally Posted by ze_shark
If you want to increase turn in/turn out grip (i.e. reduce understeer), would it make sense to start by making sure that your rear track is not too wide, and then work on front camber ? More rubber is not always the best solution.
What occurs: Loose, rear tires slide out first.
Opinion: Oversteer can be dangerous, especially at high speeds.
Tips to Correct (hint: change one thing at a time and test)
Lower front tire pressure.
Lower front tire pressure.
Raise rear tire pressure.
Stiffen front shocks.
Soften rear shocks.
Raise front end.
Lower rear end.
Reduce rear track.
Install taller front tires.
Install shorter rear tires.
Install narrower front tires.
Install wider rear tires.
Stiffen front sway bar.
Soften rear sway bar.
More front toe in.
Increase rear toe in.
Reduce front negative camber.
Reduce positive caster.
Stiffen front springs.
Soften rear springs.
May need more rear suspension travel.
Install wider rear wheels.
Use harder front compound if possible.
Use softer rear compound if possible.
Add weight to front of vehicle.
Remove weight from rear of vehicle.
Driver may be going in too deep.
Driver may be getting on the throttle to early.
High Speed. Increase rear wing downforce.
Too much rear brake.
Vehicle slides and is easy to drive at limit but
does not corner to full potential.
Raise front and rear tire pressures slightly.
Suspension may be too soft.
Shocks may be too soft.
Roll centers may be too high.
Lower vehicle.
Tires may be too hard.
Widen track front & rear.
Last edited by cjv; 01-06-2007 at 12:09 AM.
#11
01-05-2007, 11:46 PM
Originally Posted by skojasevic
i notice most of you guys have 235's up front and 315s in rear
i was just curious why i dont see more people going for a bigger size up front, maybe a 255 or 265 ?
im sure you can find a proper size, thats wider and keeps the same rotating diamter as the rears ...
i was just curious why i dont see more people going for a bigger size up front, maybe a 255 or 265 ?
im sure you can find a proper size, thats wider and keeps the same rotating diamter as the rears ...
I use 265's up front and 335's in the rear. I also use 18" wheels, 10 x 18 front and 12.5 x 18 rear. The 996tt's suspension geometry isn't really designed for 19" tires. Your choice of tires has alot to do with how you want to use your car. Don't let anyone tell you that one size is best for all applications.
At least not track, autocross or twisty road applications. I wouldn't know what size tires in 18's or 19's would be best for drag racing. Not my cup of tea.
Last edited by cjv; 01-05-2007 at 11:54 PM.
#12
01-06-2007, 08:47 AM
Originally Posted by cjv
skojasevic,
I use 265's up front and 335's in the rear. I also use 18" wheels, 10 x 18 front and 12.5 x 18 rear. The 996tt's suspension geometry isn't really designed for 19" tires. Your choice of tires has alot to do with how you want to use your car. Don't let anyone tell you that one size is best for all applications. At least not track, autocross or twisty road applications. I wouldn't know what size tires in 18's or 19's would be best for drag racing. Not my cup of tea.
I use 265's up front and 335's in the rear. I also use 18" wheels, 10 x 18 front and 12.5 x 18 rear. The 996tt's suspension geometry isn't really designed for 19" tires. Your choice of tires has alot to do with how you want to use your car. Don't let anyone tell you that one size is best for all applications.
At least not track, autocross or twisty road applications. I wouldn't know what size tires in 18's or 19's would be best for drag racing. Not my cup of tea.What modifications are required to run the tire sizes you are using? What suspension setup do you have and how much is your car lowered, if any? What offset is required on the wheels, and which wheels are you running? I am interested in doing the same thing you have done with tire sizes, but don't know what is involved. what tire are you running?
Thanks,
Al
#14
01-06-2007, 10:20 AM
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Oversteer is easier to overcome than understeer with smaller front tires if it occurs. Also, if the car is AWD than overall diameter differences f/r come into play as well. You have to stay within 4% to not get into ABS/PSM issues.
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