Are all rims lighter than stock?

[94dc2tegz]

Hey there,
Thing is I've got 17"s on my car (94 dc2 if u haven't guessed) atm but i still have the OEM 15"s in the garage. Are the 17"s better? ( i do realise 17" is bigger than 15" but yea any input would be appreciated) As in weight and wot other advantages. Or are the 'lightened rims' special rims made to a specific standard.

Thanx in advance.

[gReY-oNe]

stock rims are pretty light but there small

wat do u mena by other advantages?

weigh the two rims??

[90LAN]

u get what u pay for ....
cast wheels are heavy, forged wheels are light
but usually going bigger means more weight due to size
but also tyre weight adds to the total weight if u are going a bigger wheel

[dsp26]

what people forget to do is weigh rims WITH tyres on.....

on another note GTR32 rims are farking lighter than most aftermarket items its size

[94dc2tegz]

Cuz the OEM ones are 15" and i think are alloy's anyways but wen I got the car the dude had 17" on. Just wondering which one was better i guess I'm not really painting a picture and I really cbf taking off a wheel so I can weigh it so I guess I'll live with it unless someone can give me a def answer who's in a similar situation.

This is more or less for personal knowledge I like the look of the 17" so either way I wouldn't be putting the 15"s back on anytime soon.

[dsp26]

keep 15s IMO... you can get some real quality tyres for the price of cheapo 17s.

[STTICH]

its fair to assume tat ur 17" wheels (+tyres +pressure) would normally be much heavier than ur stock 15" wheels. most 17" do, altho there are some exception.

the dc2 15" oem rims are pretty light.

apart from the weight difference, your 17" rims would normally be wider than oem rims, which means a better grip. but u can always get wider tyres for the oem, eg: 205/50/15

one other advantage for aftermarket (larger) rims is that u'd have to run thinner tyre profile eg: 205/40/17. the thinner profile will give less body roll / tyre flex around the corner, meaning your car would feel more steadier around the corner.

having said that, most ppl would settle wth 15" and a nice set of tyres, then u're on the money :thumbsup:

[string]

17" rims of even the same weight as a set of 15" rims (both with tyres) will have more mass further from the centre. This means more torque is required to accelerate them at the same rate i.e.more drive-train loss.

OEM Integra/Civic 15's are around 8kg or so, give or take depending on which specific one you choose but they've all got about the same ammount of metal in em. The DC2R rims are a little lighter, but far less than an aftermarket (expensive$$) forged item.

You get what you pay for, and unfortunately unspring weight is really expensive to remove.

Good track tyres have very stiff side-walls, meaning that you can run higher profiles and still experience good performance unlike standard street tyres which flatten a lot under cornering loads without serious pressure.

[dsp26]

40 Profile or less tyres at their recommended tyre pressure (~40-42psi) combined with stiff track setup sussy sucks arse on roads... even on humps.

[defect]

fat 5s should be lighter than most 17s.

but japs have some lightweight forged rims which weight 4-5kgs each.

[string]

Only 6" wide though, which will affect tread width even on the same with tyre (to a degree obviously).

[playtime]

im on 205/40R17s...

is the whole circumference of the tyre the same as a 205/50R15?

[Limbo]

just rem that the lighter the rim the easier it is to damage/buckle.
you will always make better 1/4 mile runs with smaller rims, but the large ones do handle better and look nice. Depends on what you want.

You can get lightweight 17s also. With all the VTIR and type R range they are quite light already, all around the 5.5kg without tyres. You can get lighter rims. lightest i've seen is around 4kg, but you really gotta look after those cos they buckle if you hit potholes. Note all the light weight ones aren't cheap

[90LAN]

forged rims are lighter and stronger than most cast rims
so doesnt always means they will buckle easier
all wheels buckle under the right conditions
ce28's are the lightest wheel for 15's 2.8 kgs
hence the name ....



just rem that the lighter the rim the easier it is to damage/buckle.
you will always make better 1/4 mile runs with smaller rims, but the large ones do handle better and look nice. Depends on what you want.

You can get lightweight 17s also. With all the VTIR and type R range they are quite light already, all around the 5.5kg without tyres. You can get lighter rims. lightest i've seen is around 4kg, but you really gotta look after those cos they buckle if you hit potholes. Note all the light weight ones aren't cheap

[gelo]

forged rims are lighter and stronger than most cast rims
so doesnt always means they will buckle easier
all wheels buckle under the right conditions
ce28's are the lightest wheel for 15's 2.8 kgs
hence the name ....

2.8kg's?
where did you get that figure from
i dont think they are that light
maybe if they are like 15x4 or something

[roar]

yer...theyre not 2.8kg

15x6.5 4x100 ce28ns are 3.8kg

[90LAN]

rays forged rims are name after their weight for a 15x6 rim
ce28 and te37 the no's being the weight of their lightest wheel in the 15 inch range, while the letters are the model and code for being forged .....
coloum 4 from the left ......

http://i144.photobucket.com/albums/r187/90LAN/rays.jpg

[94dc2tegz]

sorry to bring this back up but here we go again,

i've got fat5's 195/55/15 vs the ones i'm currently using 205/40/17

they both workout roughly the same diameter (15's are slightly smaller but only so minimal)
but ur saying that the 15's will run better simply cuz the main mass is closer to the center?

I'll be needing new rubber though for the 15's so i think Ill b going for 195/50/15 instead of the 55's that are currently sitting on them. This works out to be almost an inch difference (0.77in). So hypothetically a good set of rubber on the 15's vs my current 17's will be a lot better for handling and acceleration?

[SHIFTY]

the smaller the rims the better..

also the weight makes a big difference...

15s is the optimum size for motor sport on smaller cars.. the only reason race cars would go bigger is because of brakes...

the smaller the better.. lighter, less diameter = faster...

[beeza]

I got some light 15's for my EK1 sedan.Can't wait to get rid of the heavy 17's.

[AKmotorworks]

Ivan, heres a test you can do. Get a chain about 1 metre long and put a weight at the end of it. swing it around, remember how much force u needed to spin it.

Now do it again with the weight closer to your hand, which is easier? Its a basic basic example and probably not very good, but you get the idea.

Not only this, but the sidewall being higher gives you more ability to alter the contact patch of the tyre onto the road. Those fat 5 15's you have will be a night and day difference :)

Andy

[dahon]

i say u should get 205/50/r15s.
and yeh shop around for great tyres. tyres definately make a difference in how your car handles just as much as handling modifications.

[Limbo]

rays forged rims are name after their weight for a 15x6 rim
ce28 and te37 the no's being the weight of their lightest wheel in the 15 inch range, while the letters are the model and code for being forged .....
coloum 4 from the left ......

http://i144.photobucket.com/albums/r187/90LAN/rays.jpg


mate based on what i found on the net they are around 3.8kg, pretty light but not 2.8kg.

They are 8.49 pounds which is 3.8kg

http://www.upgrademotoring.com/wheels/ce28n.htm

[<4n'D>]

stock rims are almost always forged and you need to pay top dollar for that kind of construction in aftermarket wheels. forged construction is almost always stronger than cast construction with some exceptions. also, grip doesnt always depend on the wheel size but also the tyre width. for the price of a crap set of 17s you can get yourself a really good set of 15s (tyres) - taking into account that 17s are also heavier it makes more sense to just stick with 15s...

[Limbo]

P.S If you can prove me wrong on the CE28s please do cos i'll be buying a set if they are that light

[scyt7e]

they'ren ot 2.8kg i have a set and weighed them before they went on my car 15 x 6.5 are around 4kg... 4.1 i think

but definately not 2.8kg :thumbsup:

the regas sitting here weight slightly less i think at 3.9 kg

[JohnL]

Ivan, heres a test you can do. Get a chain about 1 metre long and put a weight at the end of it. swing it around, remember how much force u needed to spin it. Now do it again with the weight closer to your hand, which is easier? Its a basic basic example and probably not very good, but you get the idea.

I know a theoretical difference will exist with a higher moment of inertia with more mass closer to the outside of the wheels, but is this really enough to make a noticable difference to acceleration (or conversely, deceleration, because what goes up must come down)?

It may well be a significant issue for a competition car (especailly a drag car), but will it actually be noticable without a stop watch? And even then, is it more than just a slight affect? Does anyone have numbers to back it up, i.e. back to back acceleration times with higher and lower moment of inertia wheels, excluding any affect that may be caused by grippier or less grippy rubber?

The affect of lighter wheels would be similar in principle to fitting a lighter flywheel, but the affect of a lighter flywheel should in theory be far greater due to the often very substantial difference between the mass of a light and heavy flywheel, and the much greater difference in rotational speeds between 'low' rpm and high rpm, being a difference in 1000s of rpm whereas with wheels it's going to be far less rpm at most. E.g. if we assume a 1/1 gear ratio and a final drive of say 3.9 then at 7000 engine rpm the wheel rpm will only be 1700rpm, and only this high once at the end of the run whereas the high end of engine rpm will be seen several times during the run (i.e. accelerating up to that rpm several times).

The forces and energies involved will I think increase exponentially as rpm rise, becoming very substantial at the sort of rpm the engine sees but far less at wheel rotational speeds (even if we multiply the forces / energies X 4 because there are four wheels and only one flywheel).

I'm just having trouble seeing rotational wheel inertia related to wheel mass as being a significant deal (especially for a road car), but I do see a reduction in unsprung weight being more significant for handling purposes, and the real reason you want to keep wheel mass low.


Not only this, but the sidewall being higher gives you more ability to alter the contact patch of the tyre onto the road. Those fat 5 15's you have will be a night and day difference :)

Agreed, ultra low profile tyres on huge diameter rims are unlikley to work as well as tyres with a more reasonable profile that allow adequate sidewall deflection (all else being equal), especially for road cars that have to run on real roads. Cars fitted with such wheels / tyres are a sure sign of the car owner being a 'fashion victim'.

[AKmotorworks]

I wont get into any arguments over anything, but a street car definately sees gains by switching wheels.

Numbers is going to be hard to show, but why not just get a set of 15s and 17s and go for a drive, u will notice it.

[string]

Some rough numbers. An 8kg tyre weight centred arount 25cm radius wrapped to a 8kg rim weight centred around 19cm spinning from 2000engine rpm to 8000rpm with 4.4 final drive, 3.3 first gear in 3SECONDS will require 3.2Nm at the engine. Reducing the rim weight to 4kg reduces the torque requirement to 2.6Nm.

Roughly increasing rim diameter by a little bit pushing the centre of rim mass out to 22cm and centre of tyre mass out to 28cm and increasing rim mass to 10kg gives a 4.4Nm requirement, reducing weight to 5kg gives 3.4Nm.

Conversely, an evenly distributed mass flywheel of 7.5kg diameter 25cm spinning in the same time requires 12Nm of torque, reducing to 4kg gives us 6.5Nm.

Not that much when your motor is putting out 175+Nm but it all adds up. But also shows that wheel inertial load is not insignificant. Total rotational weight is important, not just the rim. My 15" tyres weigh as much as the rims they are mounted on.

* All results rough and rounded (I=MR^2 or MR^2/2 for flywheel, T=I.a)

[beeza]

I see you've thought this out :)

[JohnL]

Some rough numbers. An 8kg tyre weight centred arount 25cm radius wrapped to a 8kg rim weight centred around 19cm spinning from 2000engine rpm to 8000rpm with 4.4 final drive, 3.3 first gear in 3SECONDS will require 3.2Nm at the engine. Reducing the rim weight to 4kg reduces the torque requirement to 2.6Nm.

Roughly increasing rim diameter by a little bit pushing the centre of rim mass out to 22cm and centre of tyre mass out to 28cm and increasing rim mass to 10kg gives a 4.4Nm requirement, reducing weight to 5kg gives 3.4Nm.

You seem to be talking about a single wheel, so the totals must be X 4? So in your examples we'd be looking at torque total of; 12.8, 10.4, 17.6 and 13.6Nm?

It would be easier to understand actual affects if we had examples for a given torque and rotational mass / moment increase on elapsed time to X engine speed (or road speed).


Conversely, an evenly distributed mass flywheel of 7.5kg diameter 25cm spinning in the same time requires 12Nm of torque, reducing to 4kg gives us 6.5Nm.

Not that much when your motor is putting out 175+Nm but it all adds up. But also shows that wheel inertial load is not insignificant. Total rotational weight is important, not just the rim. My 15" tyres weigh as much as the rims they are mounted on.

Assuming your numbers to be correct, it looks quite significant, substantially more so than even a light flywheel. I'm surprised!!

[string]

It was for all 4 wheels. And the numbers are correct, but only for a primitive model of the real thing - but it does illustrate that it is a small torque requirement, but not insignificant by any degree when you start to account for all the rotating parts.

I don't understand what you are saying would be better for understanding. I like the format of torque usage given a constant time and end constraints. If you don't want time to be the constant then you might have to figure that out for yourself :)

[JohnL]

It was for all 4 wheels.

Ah, I'm less surprised now! I was having at least some trouble thinking the overall wheel mass affect might be greater than a similar affect at the flywheel.


And the numbers are correct, but only for a primitive model of the real thing - but it does illustrate that it is a small torque requirement, but not insignificant by any degree when you start to account for all the rotating parts.

I wasn't meaning to imply they were likely to be incorrect, but I am a bit skeptical by nature.


I don't understand what you are saying would be better for understanding. I like the format of torque usage given a constant time and end constraints. If you don't want time to be the constant then you might have to figure that out for yourself :)

For me it would just be more intuitive to consider torque as the constant, and mass and time as the variables. Works either way.

Thanks for posting some actual numbers, even if from a "primtive model" they are helpful to understand what's going on.

[Limbo]

i was watching best motoring when they tested the lighter rims on a EVO 8 or 9 can't rem, anyway they said on the track the lighter rims made very slight difference, but had better feel.

[string]

For me it would just be more intuitive to consider torque as the constant, and mass and time as the variables. Works either way.
I'll politely disagree. When looking at the big picture, the inertial loads of the wheels and flywheel isn't the major load on the motor; moving the chassis forward is. Finding out how much extra time a given torque takes to spin different mass rims is a pointless exercise - whatever torque is required to take them to speed in a given time, will be applied. It is a minor load in the end, with the bulk of the outcome depending on the mass of the chassis not the wheels.

If the torque requrement was 50% or more of the engine torque then I agree with your thinking. Then, how fast you can spin up the (now giant) wheels really matters.

[butterfingers]

I actually found my ek feels faster after upgrading to 17" enkei ev5s. Hmmm

[androo]

I actually found my ek feels faster after upgrading to 17" enkei ev5s. Hmmm

Is it because the ride is now bumpier? Makes you feel like you're moving more rapidly?

Personal experience? I've ran 15" stockies, 16" rims and 17" rims. The 17"s were much bumpier than the others. The 15"s are the most comfy and acceleration felt the best. It was also easiest to wheel spin (but it's also the thinnest rim). I'm currently running the 16"s because they are a good compromise on looks and handling. But I can't stand 17"s on an Integra. OP, I know everyone is trying to give you advice and you're somewhat listening, but instead of wasting time on this forum 'trying' to figure it out, get off your butt on a weekend some time and change the wheels over for a quick test. Should take you less than an hour and you will personally feel the difference. I promise you it will be dramatic. I bought my car with 17"s. After running them for a while I got 15" stockies and they made a world of difference.