Performance Comparing 16", 17" Rims.
02-18-2001, 11:39 PM
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pfb-
Huh? I always thought you maintained tire air volume when calculating plus sizing, especially concerning ride quality.
Case in point-
Plus 1 sizing for a standard 205/50R15 is 215/45R16. So you go up 10mm in width, but lower the sidewall height by 5%, which is roughly the same tire volume. I;m not sure about wheel sizing on a plus one, but that's how GRM does it in one of their articles they researched from the Tire Rack. So, to go to bigger wheels, you need to go to a wider tire. The limit of the wheel/tire combo ends up being a combination of what actually fits in the wheel well, and what sidewall/casing width is available to the given size wheel.
Huh? I always thought you maintained tire air volume when calculating plus sizing, especially concerning ride quality.
Case in point-
Plus 1 sizing for a standard 205/50R15 is 215/45R16. So you go up 10mm in width, but lower the sidewall height by 5%, which is roughly the same tire volume. I;m not sure about wheel sizing on a plus one, but that's how GRM does it in one of their articles they researched from the Tire Rack. So, to go to bigger wheels, you need to go to a wider tire. The limit of the wheel/tire combo ends up being a combination of what actually fits in the wheel well, and what sidewall/casing width is available to the given size wheel.
02-19-2001, 06:35 AM
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pfb-
It's not your calculation or how you derive it that confuses me.
I've always assumed when going to plus sizings you retained tire volume, not contact patch. Again, the reason is for ride quality. If you don't maintain constant volume (decrease it in your examples) between plus sizings, you increase ride harshness- and a negative side effect is that the wheel isn't as well protected.
Going to your version of plus sizing is merely cosmetic, and decreases ride quality, and in some cases, handling quality. The way I've described it, going to a plus size will maintain ride quality, achieve the cosmetic goal, and increase the contact patch at all four corners which will in all probablity be a positive for handling.
Barry and Prolene-
In most cases, going to plus sizings the way I've described them will benefit handling. There MAY be a slight loss of acceleration if the tires are significantly heavier (3-6lb variance)- which is why choosing a good tire is so pertinent. The effect is not so pronounced if the wheels are heavier (give or take 3-6 pounds)- the reasons being given by UL in the other thread.
This is why King Motorsports uses Kosei K1 wheels with Hoosiers on their Motorola Cup ITR cars- the wheels are cheap, strong, and relatively lightweight (although not when compared to the true lightweights in the category) but use the lightest, stickiest, stiffest, widest tire they can get on the wheel- going from a stock 195/55R15 to 225/45R15, with wheels increasing from 15x6JJ to 15x7JJ.
[Edited by GTRPower on 02-19-2001 at 07:45 AM]
It's not your calculation or how you derive it that confuses me.
I've always assumed when going to plus sizings you retained tire volume, not contact patch. Again, the reason is for ride quality. If you don't maintain constant volume (decrease it in your examples) between plus sizings, you increase ride harshness- and a negative side effect is that the wheel isn't as well protected.
Going to your version of plus sizing is merely cosmetic, and decreases ride quality, and in some cases, handling quality. The way I've described it, going to a plus size will maintain ride quality, achieve the cosmetic goal, and increase the contact patch at all four corners which will in all probablity be a positive for handling.
Barry and Prolene-
In most cases, going to plus sizings the way I've described them will benefit handling. There MAY be a slight loss of acceleration if the tires are significantly heavier (3-6lb variance)- which is why choosing a good tire is so pertinent. The effect is not so pronounced if the wheels are heavier (give or take 3-6 pounds)- the reasons being given by UL in the other thread.
This is why King Motorsports uses Kosei K1 wheels with Hoosiers on their Motorola Cup ITR cars- the wheels are cheap, strong, and relatively lightweight (although not when compared to the true lightweights in the category) but use the lightest, stickiest, stiffest, widest tire they can get on the wheel- going from a stock 195/55R15 to 225/45R15, with wheels increasing from 15x6JJ to 15x7JJ.
[Edited by GTRPower on 02-19-2001 at 07:45 AM]
02-19-2001, 06:49 AM
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[QUOTE]Originally posted by Barry WY Silver/Black '01
My take home from the thread was that handling is improved by the larger rim, but perhaps not significantly, because of possible camber not to the ideal as GTRPower stated, sidewall issues and such.
GTRPower also stated: "The limit of the wheel/tire combo ends up being a combination of what actually fits in the wheel well, and what sidewall/casing width is available to the given size wheel." This makes sense to me.
After pondering all these issues, I do not think the S2000 was engineered with a very wide (255 and up) tire in mind. I think a 16" rim is a nice size for a 245 tire, given the proper width rim. Kumhos have comp tires in 245/45/16, but not 245/40/17, at least at Tirerack. The latter size is needed if one wants to keep overall diameter about the same; otherwise you have another 1" diameter with which you are running. Having a proper (Spoon or equiv) 16" rim will allow more flexibility (no pun
) to tire brand if I want to run Kumhos and also allows running 245s, the widest I would go.
[Edited by Prolene on 02-19-2001 at 08:10 AM]
Yes or no? Is handling significantly improved with 17" rims over that of 16"?
GTRPower also stated: "The limit of the wheel/tire combo ends up being a combination of what actually fits in the wheel well, and what sidewall/casing width is available to the given size wheel." This makes sense to me.
After pondering all these issues, I do not think the S2000 was engineered with a very wide (255 and up) tire in mind. I think a 16" rim is a nice size for a 245 tire, given the proper width rim. Kumhos have comp tires in 245/45/16, but not 245/40/17, at least at Tirerack. The latter size is needed if one wants to keep overall diameter about the same; otherwise you have another 1" diameter with which you are running. Having a proper (Spoon or equiv) 16" rim will allow more flexibility (no pun
) to tire brand if I want to run Kumhos and also allows running 245s, the widest I would go.[Edited by Prolene on 02-19-2001 at 08:10 AM]
02-19-2001, 03:01 PM
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Prolene:
Check out this article at
http://www.grassrootsmotorsports.com/
click "tech topics" in the web features box, then "plus sizing". Fairly comprehensive article with lap times and ride quality impression for 14,15,16,17" tires on same car.
Check out this article at
http://www.grassrootsmotorsports.com/
click "tech topics" in the web features box, then "plus sizing". Fairly comprehensive article with lap times and ride quality impression for 14,15,16,17" tires on same car.
02-19-2001, 04:26 PM
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cdelena,
That is actually a good point and one that I have picked up from the stuff I have read on this forum. Problem is, unless someone has done a review of a particular tire, I'm not aware there is any way to tell how stiff a particular tire's sidewall is. Like everything else when it comes to changing something on your car, one should get as much information as possible - be an informed modder!
That is actually a good point and one that I have picked up from the stuff I have read on this forum. Problem is, unless someone has done a review of a particular tire, I'm not aware there is any way to tell how stiff a particular tire's sidewall is. Like everything else when it comes to changing something on your car, one should get as much information as possible - be an informed modder!
02-19-2001, 05:26 PM
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Originally posted by GTRPower
I've always assumed when going to plus sizings you retained tire volume, not contact patch
I've always assumed when going to plus sizings you retained tire volume, not contact patch
I completely agree, however, that a primary advantage of going to a larger rim is the shorter, (presumably) stiffer sidewall which improves handling.
[Edited by pfb on 02-19-2001 at 08:54 PM]
02-19-2001, 05:54 PM
#20
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Something else to consider from the GRM test is that the tires got wider (as they should to maintain air volume) as wheel diameter was increased.
This will usually result in the contact patch getting wider side to side and shorter front to rear. This usually aids lateral acceleration and, as such, doesn't necessarily indicate that a larger wheel handles better (even though I believe they have handling advantages).
These comparisons are always tough to make, but I believe the general assertion that larger wheels with wider tires will improve handling is true.
UL
This will usually result in the contact patch getting wider side to side and shorter front to rear. This usually aids lateral acceleration and, as such, doesn't necessarily indicate that a larger wheel handles better (even though I believe they have handling advantages).
These comparisons are always tough to make, but I believe the general assertion that larger wheels with wider tires will improve handling is true.
UL