MARLON1211
Active member
is it better to run the stock 15s on a qtr mile, or just run it with my bling bling 17s.
Running w/ 17s
- Thread starter MARLON1211
- Start date
A
Anonymous
Guest
Actually my 17s are light, if am not mistaken a tad lighter that my stock 15s. Mostly am looking for is the performance.
MARLON1211
Active member
Whoow i replied to you and i see my self as a guest well mayb an error or something.
BraveUlysses
New member
What it comes down to is how much the wheels weight and how close the mass of the wheels is to the center. Overall, this is hard to measure, but most likely, the 17's are heavier in this respect.
The stock alltrac wheels are heavy as hell though, so take this all as you will.
The stock alltrac wheels are heavy as hell though, so take this all as you will.
MARLON1211
Active member
MTBgael, thats a good advice.
omgitsroy326
New member
yes it will be hard to messure the inertia of the two different rims, but you can take a look at the two and kinda guess and estimate which would have a larger inertia.
But if you take rod ... thinking that it's one spoke then ... also the rod is rotating through one end then the equation is I = 1/3 m* L ^2
or say a thin walled hallow sphere I = 2/3 M R^2... you can see that as u get away furthur from the radius the Inertia increases by some fraction time the radius or length to the second power.
So if you have R1 = (17/2) ^ 2 = 72.25
R2 = (15/2) ^ 2 = 56.25
this is if the mass and the design are the same then r2/r1 = 77% or 33% more inertia..
and if we take what mebgael said "The 15s have less rotating mass, because the weight is closer to the hub. 17s have more weight further from the hub, so they will slow you down."
then you can estimate and guess that the diameter for the 15 may be reduced to to somethin smaller and closer to the hub... while the 17 diameter stays constant. so that previous 33% different can be increased to say maybe 44%. I could be wrong.... but this is how i look at it when i get my rims.... I previously had 18 by 9.5 and it really screwed me up on my previous car... u really notice a difference.
But if you take rod ... thinking that it's one spoke then ... also the rod is rotating through one end then the equation is I = 1/3 m* L ^2
or say a thin walled hallow sphere I = 2/3 M R^2... you can see that as u get away furthur from the radius the Inertia increases by some fraction time the radius or length to the second power.
So if you have R1 = (17/2) ^ 2 = 72.25
R2 = (15/2) ^ 2 = 56.25
this is if the mass and the design are the same then r2/r1 = 77% or 33% more inertia..
and if we take what mebgael said "The 15s have less rotating mass, because the weight is closer to the hub. 17s have more weight further from the hub, so they will slow you down."
then you can estimate and guess that the diameter for the 15 may be reduced to to somethin smaller and closer to the hub... while the 17 diameter stays constant. so that previous 33% different can be increased to say maybe 44%. I could be wrong.... but this is how i look at it when i get my rims.... I previously had 18 by 9.5 and it really screwed me up on my previous car... u really notice a difference.
A
Anonymous
Guest
I recently installed a set of 17s on my st165 Celica.
"Is that possible" you ask?
Sure... some assembly required.
I had these 17s on a different car but I needed a set of road tires to make the long trip to a Rally out of town (I didn't want to use up my super soft Rally tires on the pavement there and back).
The 17s were 215/40 in front, not a big deal. But 135/35 in the rear! No, they wouldn't clear the spring perch. However, they didn't need much to do so.
With some "light persuasion" with a 5 lb sledge, I managed to dent the sring perch just enough to allow the tire to pass by cleanly.
Now, nobody would go around recommending folks to "whack on their suspension with a huge hammer", but some precusion tapping with a punch can dimple a piece of steel without loosing the integrity of the part.
So now, I have that full wheel well 17 inch tire look WITH that rear wheel drive wider rear end look. Pretty neat actually.
The down side is, that I will only ever have those wheels on there for long, road trips to a rally. And even that is going to be rare with the new race trailer.
Even so... folks, it CAN be done. 17s WILL fit an st165 even if it has 235s on the rear, LOL!!!
I'll dig up a pic.
Best,
Scott "DKOV" Kovalik
-------------------------
"Is that possible" you ask?
Sure... some assembly required.
I had these 17s on a different car but I needed a set of road tires to make the long trip to a Rally out of town (I didn't want to use up my super soft Rally tires on the pavement there and back).
The 17s were 215/40 in front, not a big deal. But 135/35 in the rear! No, they wouldn't clear the spring perch. However, they didn't need much to do so.
With some "light persuasion" with a 5 lb sledge, I managed to dent the sring perch just enough to allow the tire to pass by cleanly.
Now, nobody would go around recommending folks to "whack on their suspension with a huge hammer", but some precusion tapping with a punch can dimple a piece of steel without loosing the integrity of the part.
So now, I have that full wheel well 17 inch tire look WITH that rear wheel drive wider rear end look. Pretty neat actually.
The down side is, that I will only ever have those wheels on there for long, road trips to a rally. And even that is going to be rare with the new race trailer.
Even so... folks, it CAN be done. 17s WILL fit an st165 even if it has 235s on the rear, LOL!!!
I'll dig up a pic.
Best,
Scott "DKOV" Kovalik
-------------------------
celicaracer18
New member
just wondering but if you had really light wieght 17s with some good tires couldn't you get alot more traction
alltracman78
Active member
That's what the awd is for 
celicaracer18
New member
yeah, forgot about that
i don't have tht advantage
i don't have tht advantage
A
Anonymous
Guest
Apparently THIS is the ONLY thread on this entire forum on which I can post.
My name and password works HERE and here only.
If someone reads this and wants to help out, can you post the following response to a thread titles "skid plates for 165" under CLUB CHAT...
Here's the question posted by TRDriver: "is there anybody that makes skid plates for the 165? if not, what do i make them out of and what should they cover and where could i bolt them up? thanks alot!"
PLEX replied that I had them built by Tap Plastics.
MY REPLY:
Tap Plastics did not build them for me, I built them myself but I purchased the materials from Tap Plastics. I then took them home and cut, heated, shaped and installed them.
All the materials I bought from Tap are High Density Polyethalene. I bought a 4x4 sheet of 1/2 inch and a 4x8 sheet of 1/4 inch.
The half inch is the front portion under the engine to the cross beam roughtly at the axle and the rest of the underside is coated with the 1/4 inch. Of course, there are special cuts and spacings to be made there too. And, the under plates have to be shaped to avoid catching any ground, road or excess amounts of mud and debris which racing.
Let's not forge the MOUNTS. Steel plates and mounts have to be welded onto the bottom of the car to accept the new skids and hold them in place. I bult my mounts to accept large button head, hex drive bolts that are tapped into the mounts and chassis. These done have a head that can grab debris or the ground and adds to the overall "slickness" of the kit.
Also, some consideration must be given to the exhaust line. Even though the PolyE has an extremely high flash point, it will melt if it sits right up agains the exhaust. I have about a 1/3 of an inch between my Poly and the down pipe in one particular place and it's got nothing but a little discolored. It's not really going to burn but it might get stinky if it actually TOUCHES the exhaust for a long amount of time at race pace.
The reason for Polyethalene rather than aluminum or steel plating is that the Poly is smooth and slick allowing the car to easily slide over any obstacles yet is strong enough to take the toughest of hits. Plus, the flxible nature of the stuff allows it to actually help absorb the hits.
Metal plates take the hit and dent. Then they are shaped that way. The next hit you take, then, does the damage. The poly, even if it is pushed in, pops right back out as if nothing has ever happened.
Those of you that have seen me run, know just how strong this stuff is!!!
If anyone want to drop by and check my kit out, I'm happy to share. In fact, I still have my templates and such for making more if anyone's interested.
Best,
Scott "DKOV" Kovalik
-------------------------
My name and password works HERE and here only.
If someone reads this and wants to help out, can you post the following response to a thread titles "skid plates for 165" under CLUB CHAT...
Here's the question posted by TRDriver: "is there anybody that makes skid plates for the 165? if not, what do i make them out of and what should they cover and where could i bolt them up? thanks alot!"
PLEX replied that I had them built by Tap Plastics.
MY REPLY:
Tap Plastics did not build them for me, I built them myself but I purchased the materials from Tap Plastics. I then took them home and cut, heated, shaped and installed them.
All the materials I bought from Tap are High Density Polyethalene. I bought a 4x4 sheet of 1/2 inch and a 4x8 sheet of 1/4 inch.
The half inch is the front portion under the engine to the cross beam roughtly at the axle and the rest of the underside is coated with the 1/4 inch. Of course, there are special cuts and spacings to be made there too. And, the under plates have to be shaped to avoid catching any ground, road or excess amounts of mud and debris which racing.
Let's not forge the MOUNTS. Steel plates and mounts have to be welded onto the bottom of the car to accept the new skids and hold them in place. I bult my mounts to accept large button head, hex drive bolts that are tapped into the mounts and chassis. These done have a head that can grab debris or the ground and adds to the overall "slickness" of the kit.
Also, some consideration must be given to the exhaust line. Even though the PolyE has an extremely high flash point, it will melt if it sits right up agains the exhaust. I have about a 1/3 of an inch between my Poly and the down pipe in one particular place and it's got nothing but a little discolored. It's not really going to burn but it might get stinky if it actually TOUCHES the exhaust for a long amount of time at race pace.
The reason for Polyethalene rather than aluminum or steel plating is that the Poly is smooth and slick allowing the car to easily slide over any obstacles yet is strong enough to take the toughest of hits. Plus, the flxible nature of the stuff allows it to actually help absorb the hits.
Metal plates take the hit and dent. Then they are shaped that way. The next hit you take, then, does the damage. The poly, even if it is pushed in, pops right back out as if nothing has ever happened.
Those of you that have seen me run, know just how strong this stuff is!!!
If anyone want to drop by and check my kit out, I'm happy to share. In fact, I still have my templates and such for making more if anyone's interested.
Best,
Scott "DKOV" Kovalik
-------------------------
alltracman78
Active member
2of81":3m88q9fb said:
But, a larger wheel will move the heavier part (wheel) futher out, which will make it harder to spin.
here is a pic of my ST165 with 17s: would have worked fine, except I went with 225/45 tires (wanted the Azenis bad). 215s would have fixed my problem but i didn't want to spend any more money on a car i knew i was gonna have to sell
And... yes, if you add weight to wheels and tyres, it will make more of a difference to performance than if it was something that didn't rotate. Nothing complicated here. you don't have to rely on what you hear in magazines. here is the deal, more or less. i don't feel like busting out my physics book or looking anything up, so this may be slightly less than accurate but i am sure adrian or someone can correct me.
the masses on your car can be broken up into a few categories: sprung, unsprung, rotating, maybe a few more that don't apply here. in each case we are dealing with inertia, which is the resistance to being accelerated. however, rotating inertia has a more complicated formula than the other two.
sprung weight is weight that is carried by the suspension. better to add sprung weight than unsprung weight (i.e., brakes, wheels& tires). if you add unsprung weight, the ability of the suspension to keep the wheels on the road at all times goes down (if you have an oscillating lever and put weight at the end, the frequency goes down. this is what is happening with your suspension. you are making it harder for the shocks to control all that weight at the end of this lever).
however, if you add weight to your wheels and tires, you will not only be adding unsprung weight but rotating mass. this increases rotational inertia according to the equation 1/12 Mass X Radius^2 . Of course, that's not exactly what it is for a wheel because it's not solid and it has spokes and stuff, but you can see that you can't really say adding weight to wheels makes 8 times as much difference as adding weight to the rest of the car. It depends on where on the wheel you add it, the length of your suspension arms, and many other variables. However, you can see that you are adding both rotational inertia (making it harder to accelerate and decelerate the wheels) and unsprung mass (degrading suspension function), so this is something to be avoided.
And... yes, if you add weight to wheels and tyres, it will make more of a difference to performance than if it was something that didn't rotate. Nothing complicated here. you don't have to rely on what you hear in magazines. here is the deal, more or less. i don't feel like busting out my physics book or looking anything up, so this may be slightly less than accurate but i am sure adrian or someone can correct me.
the masses on your car can be broken up into a few categories: sprung, unsprung, rotating, maybe a few more that don't apply here. in each case we are dealing with inertia, which is the resistance to being accelerated. however, rotating inertia has a more complicated formula than the other two.
sprung weight is weight that is carried by the suspension. better to add sprung weight than unsprung weight (i.e., brakes, wheels& tires). if you add unsprung weight, the ability of the suspension to keep the wheels on the road at all times goes down (if you have an oscillating lever and put weight at the end, the frequency goes down. this is what is happening with your suspension. you are making it harder for the shocks to control all that weight at the end of this lever).
however, if you add weight to your wheels and tires, you will not only be adding unsprung weight but rotating mass. this increases rotational inertia according to the equation 1/12 Mass X Radius^2 . Of course, that's not exactly what it is for a wheel because it's not solid and it has spokes and stuff, but you can see that you can't really say adding weight to wheels makes 8 times as much difference as adding weight to the rest of the car. It depends on where on the wheel you add it, the length of your suspension arms, and many other variables. However, you can see that you are adding both rotational inertia (making it harder to accelerate and decelerate the wheels) and unsprung mass (degrading suspension function), so this is something to be avoided.