It's the way I'm going at least!
Do you think 18's are too big for a S13??
ACK!!
I thought I mentioned this problem in my previous post, but perhaps you were bored reading it and skipped over...
Changing your tire's Overall Diameter(OD) changes your car's "effective axle ratio". Meaning, that instead of actually changing the pinion/ring gear ratio, you are altering the tire's revolutions per mile ratio. The result of putting a larger tire on is the same as altering your axle's gear ratio, so it is called the "effective axle ratio."
If you put a taller OD tire on your car, the car's effective axle ratio becomes numerically lower, giving you a higher top speed(barely, you won't notice with the changes we're talking about here), and also slowing acceleration time. The reason for the slower acceleration is you have now lengthened the "arm" that the engine's torque must turn...not to mention the added weight of big rims... That is the simplest explanation i can think of at this early hour.
Notice that if you put on a smaller tire, your top speed would be lower(again, ever so slightly), and your car would feel as though the engine has more torque. By using a shorter tire, you have shortened the length of the "arm" that the engine's torque must turn.
Rotational mass can also be called rolling mass. Any increase will make your car's components work harder than intended....thereby causing your car to feel less responsive. The usual suspects are affected: engine torque feels lower, because of greater weight that the engine's torque must now turn(causing the car to "feel" slower on acceleration), and braking will suffer, because the brakes must now slow the turning effect of a greater than OEM-intended mass(your heavy wheel).
If you want some easy proof about mass and how it affects responsiveness:
Take a bowling ball and a basketball...throw each one at your best friend as hard as you can. Which ball accelerated with the least amount of effort? Which ball was easier to slow down when your friend tried to catch them? Imagine the extra work an OEM-grade car must do when you add rotational mass.
A crappy analogy, but you get the idea.
I thought I mentioned this problem in my previous post, but perhaps you were bored reading it and skipped over...
Changing your tire's Overall Diameter(OD) changes your car's "effective axle ratio". Meaning, that instead of actually changing the pinion/ring gear ratio, you are altering the tire's revolutions per mile ratio. The result of putting a larger tire on is the same as altering your axle's gear ratio, so it is called the "effective axle ratio."
If you put a taller OD tire on your car, the car's effective axle ratio becomes numerically lower, giving you a higher top speed(barely, you won't notice with the changes we're talking about here), and also slowing acceleration time. The reason for the slower acceleration is you have now lengthened the "arm" that the engine's torque must turn...not to mention the added weight of big rims... That is the simplest explanation i can think of at this early hour.
Notice that if you put on a smaller tire, your top speed would be lower(again, ever so slightly), and your car would feel as though the engine has more torque. By using a shorter tire, you have shortened the length of the "arm" that the engine's torque must turn.
Rotational mass can also be called rolling mass. Any increase will make your car's components work harder than intended....thereby causing your car to feel less responsive. The usual suspects are affected: engine torque feels lower, because of greater weight that the engine's torque must now turn(causing the car to "feel" slower on acceleration), and braking will suffer, because the brakes must now slow the turning effect of a greater than OEM-intended mass(your heavy wheel).
If you want some easy proof about mass and how it affects responsiveness:
Take a bowling ball and a basketball...throw each one at your best friend as hard as you can. Which ball accelerated with the least amount of effort? Which ball was easier to slow down when your friend tried to catch them? Imagine the extra work an OEM-grade car must do when you add rotational mass.
A crappy analogy, but you get the idea.
since someone already threw out my fav. offset calculator toy, i'm gonna pitch another link in:
http://www.miata.net/garage/tirecalc.html
i picked up a set of 5zigen n1r becketts (16x8, 33offset if autoimaging.com is correct) with falken 225/50R16's on them nice and cheap from jspec.com- for used wheels they were in excellent shape, but i don't think you could count on that every time. on my s13 they are pretty close to flush w/ the fenders.
i'll be ditching these tires and picking up 225/45R16 kumhos whenever i manage to burn through them, but other than that i'm happy with the setup and they'll probably be the only set of wheels i buy for this car- if i ever need more than 225mm of tire, it won't be anytime soon.
i'd call 17s unnecessary if R33 GTR wheels didn't look so damn *good*. 18s? no. just no.
http://www.miata.net/garage/tirecalc.html
i picked up a set of 5zigen n1r becketts (16x8, 33offset if autoimaging.com is correct) with falken 225/50R16's on them nice and cheap from jspec.com- for used wheels they were in excellent shape, but i don't think you could count on that every time. on my s13 they are pretty close to flush w/ the fenders.
i'll be ditching these tires and picking up 225/45R16 kumhos whenever i manage to burn through them, but other than that i'm happy with the setup and they'll probably be the only set of wheels i buy for this car- if i ever need more than 225mm of tire, it won't be anytime soon.
i'd call 17s unnecessary if R33 GTR wheels didn't look so damn *good*. 18s? no. just no.
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Nock Out Puppet
- Posts: 312
- Joined: Sun Jun 15, 2003 8:13 pm
If you get smaller rims they help rev faster. If you have larger rims they alow you to stay in 1st and second gear longer. Smaller rims are also easier on your trany. Larger rims are easier on the bearings. its a trade of. If you have a high reving engine go with smaller.On a turbo system I say go with the 18's.
Nock Out, that's incorrect. A wheel's size does not determine a tire's revolutions per mile. A simple concept called "plus-sizing" allows one to figure what tire will accomodate a larger wheel size, but keep the car maker's OEM-spec tire Overall Diameter(OD). Any reputable tire/wheel shop has booklets or lists of tire OD's, which will allow you to switch from your factory 15" wheels to 16, 17, etc...while still maintaining OD. Keeping OEM OD is important for several reasons, all of which I have explained in detail in my previous two posts.
Larger rims are not easier on the bearings. Larger rims are often protruding farther from the bearing/hub assy than OEM wheels....creating a greater "lever" using gravity acting on your car's weight as effort, causing GREATER stress loads on the bearings. Smaller rims are not necessarily easier on your transmission. Smaller "rims"...I'll assume you're speaking of wheel/tire combination that is smaller than OEM OD... will require MORE revolutions per mile. This means your transmission is doing more work than before to travel the exact same distance.
You should not try and mate a low-torque output engine such as a 4cyl with heavier, larger OD wheel/tire combination. All of this has been explained. I implore you to scroll up and please read carefully.
Larger rims are not easier on the bearings. Larger rims are often protruding farther from the bearing/hub assy than OEM wheels....creating a greater "lever" using gravity acting on your car's weight as effort, causing GREATER stress loads on the bearings. Smaller rims are not necessarily easier on your transmission. Smaller "rims"...I'll assume you're speaking of wheel/tire combination that is smaller than OEM OD... will require MORE revolutions per mile. This means your transmission is doing more work than before to travel the exact same distance.
You should not try and mate a low-torque output engine such as a 4cyl with heavier, larger OD wheel/tire combination. All of this has been explained. I implore you to scroll up and please read carefully.
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Nock Out Puppet
- Posts: 312
- Joined: Sun Jun 15, 2003 8:13 pm