315 vs 295 Comparison
#16
04-10-2017, 09:30 AM
You guys realize the specifications you are siting are just that...theoretical specifications. To really know what you have you'll have to take measurements. Variation in rolling diameters can be significantly greater that the specified dimensions.
#17
04-10-2017, 12:53 PM
Join Date: Feb 2011
Location: Lewisville, NC
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Throw tire pressures and tread wear into the equation and there will always be a variance.
What ever you do, don't install new rear tires with worn front tires. That would cause serious damage.
Basically, the further they're off, the more wear and torque transfer (wanted or unwanted). The least amount of wear would be if the front and rear tires were the same size, but then the dynamics would not be as Porsche intended.
Either way, not the point of this thread.
Later, Steve
What ever you do, don't install new rear tires with worn front tires. That would cause serious damage.
Basically, the further they're off, the more wear and torque transfer (wanted or unwanted). The least amount of wear would be if the front and rear tires were the same size, but then the dynamics would not be as Porsche intended.
Either way, not the point of this thread.
Later, Steve
#18
04-10-2017, 11:43 PM
If your car has been converted to RWD only then no problem.
If your car has not been converted to RWD then a problem.
The wheels/tires you are considering have a front/rear revs/mile of 807/825 for a difference of 18.
The stock wheels/tires of 225/40x18 and 285/30x18 have a revs/mile of 828/840 for a difference of 12.
Running 295/30x18 rear tires has the front/rear revs/mile of 828/832 for a difference of just 4.
The tire setup you are considering has the rear tires making 33% more revs per mile than the 225/40x18 and 285/30x18 wheels /tires. 33% more revs per mile is probably going to over heat the viscous coupling.
If your car isn't currently RWD only it soon will be when the front diff konks out and you have to remove it.
If your car has not been converted to RWD then a problem.
The wheels/tires you are considering have a front/rear revs/mile of 807/825 for a difference of 18.
The stock wheels/tires of 225/40x18 and 285/30x18 have a revs/mile of 828/840 for a difference of 12.
Running 295/30x18 rear tires has the front/rear revs/mile of 828/832 for a difference of just 4.
The tire setup you are considering has the rear tires making 33% more revs per mile than the 225/40x18 and 285/30x18 wheels /tires. 33% more revs per mile is probably going to over heat the viscous coupling.
If your car isn't currently RWD only it soon will be when the front diff konks out and you have to remove it.
#20
04-11-2017, 03:53 PM
Based on what I've experienced, it does look at front and rear wheel revolutions because as you increase a disparity of front to rear diameter ratios, it makes the ABS more susceptible to ice mode.
Last edited by pwdrhound; 04-11-2017 at 04:04 PM.
#23
04-12-2017, 06:25 AM
Registered User
This makes so much sense now.. I was running a 295/30/19 PSS and rubbing like crazy on one of my cars.
toyo R888 315/30/R20 12.6 section width / 11.9 tread width
Miche PSS 315/35/20 is the same size
miche PSS 295/30/19 section width 11.9 , tread width 11.5 is an oddball tire.
toyo R888 315/30/R20 12.6 section width / 11.9 tread width
Miche PSS 315/35/20 is the same size
miche PSS 295/30/19 section width 11.9 , tread width 11.5 is an oddball tire.
#25
12-06-2022, 12:44 PM
315/25zr19 vs 295/30r19 ride difference
I had a rear tire on my 2004 Carrera C4S blow out and I flat out cannot find a replacement tire (315/25zr19) anywhere! So my tire guy is telling me to just buy 2 new rear tires (295/30r19). My reluctance is 1) I hate having to buy 2 new tires when 1 blows out, and 2) I am wondering how the ride will be (rougher?)
Does anyone have insights on how the ride will be affected if I make this change?
Thanks!
Does anyone have insights on how the ride will be affected if I make this change?
Thanks!
#26
12-10-2022, 08:33 AM
Well you have larger sidewalls, so depending on the stiffness of the sidewall, you likely will have more "cushion". Probably a marginal impact on performance for everyday driving.
