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Old 6th June 2010, 10:52   #16
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Lancer_rit has already explained it quite well, but I would tend to disagree slightly in implementation:

IMHO, ideally one should maintain the same track (the distance between the centrelines of the tires - maybe different for the front and rear) as the stock car rather than the same offset.

So if you are increasing the width of your tires, you should ensure that half the width goes inwards (towards the suspension) and half out. Of course this should always be subject to physical checks to ensure for eg: there is enough clearance on the inside - If in doubt it would be better to err and go with a slightly lower offset so that the tires protrude slightly out rather than foul with the suspension

So to maintain the same track, subtract half the increase in tire width to your ET eg: if you upgrade from 155 to say 185, and your original ET was +40, your new ET should be = +40 - 0.5x(185-155)= 40-15 = 25

Now the actual ET that you choose to install would depend on a physical check of your car and a judgemental call regarding the space available between the existing wheel and the suspension vs that available on the outer face of the wheel well. Taking 25 as the base, you can decide whether you would like to mount the wheels slightly outward (subtract from 25) or slightly inward (add to 25)

Edit: @ Lancer -reread your post, guess we're saying the same thing after all - I missed reading "So, if the tyre width remains same" BTW, any reason for wanting to stay within 5-7mm of the original offset, would this apply even for large differences between the new size and the original (say 155 to 205 - not impractical for say a swift) calculated difference in ET in this case would be 25mm...

Last edited by adisag : 6th June 2010 at 11:01.
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Old 6th June 2010, 11:01   #17
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Quote:
Originally Posted by adisag View Post

So to maintain the same track, subtract half the increase in tire width to your ET eg: if you upgrade from 155 to say 185, and your original ET was +40, your new ET should be = +40 - 0.5x(185-155)= 40-15 = 25
I wouldn't recommend that - this would greatly impact the suspension setup because the weight distribution changes significantly. IIRC, from my searching when I did my wheel/tyre upgrade, you should not vary your ET too much from your original value.
Ideally, you should retain the same ET, keeping the same weight distribution on your suspension arm and steering linkage. However, some adjustment to account for increased width of wheel/tyre is beneficial to not foul up suspension / inner wheel well wall, so one has to do a balancing act.

Have to say after 2 years, and 23000km, my setup is working great, and the handling is much better due to 175/80R13 -> 195/60R15 MXV8.
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Old 21st September 2012, 00:31   #18
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Default Re: How Important Is the Offset (ET) of a Wheel During Wheel Upgrade for Various Cars

@adisag, 5-7mm is a sort of rule of thumb - for eg. from the Tyre Bible. The reason is that if we change too much, the weight distribution inside and outside the plane of wheel mounting changes significantly -> this unbalances the suspension design etc.
For eg. if the new wheel /tyre setup is 5kg heavier, you prefer to have this added in the same ratio on the inside and outside of the offset plane, than add 1kg on the inside and 4kg on the outside or vice-versa!

My upgrade now has run 52k+ kms, and still looks good :-)
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Old 21st September 2012, 03:16   #19
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Default Re: How Important Is the Offset (ET) of a Wheel During Wheel Upgrade for Various Cars

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Originally Posted by lancer_rit View Post
My upgrade now has run 52k+ kms, and still looks good :-)
Congrats! This is by no means a small achievement and I mean it.
I must have missed this thread earlier and not sure why you reviewed it after almost a year, but thanks.

I am currently in the midst of upgrading my Lancer's shoes and in doing so I have landed in weird and funny situations. More later in my next post. Tomorrow, I am getting another set of 4 alloys (3rd set to be precise) and that will probably put my mind to rest.
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Old 21st September 2012, 09:32   #20
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Default Re: How Important Is the Offset (ET) of a Wheel During Wheel Upgrade for Various Cars

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Originally Posted by Chewbacca View Post
Congrats! This is by no means a small achievement and I mean it.
...
I am currently in the midst of upgrading my Lancer's shoes and in doing so I have landed in weird and funny situations. More later in my next post. Tomorrow, I am getting another set of 4 alloys (3rd set to be precise) and that will probably put my mind to rest.
Thanks. If you post your car's alloy wheel and tyre size, I could give some hints on a good setup :-)
Good luck.
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Old 21st September 2012, 12:55   #21
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Default Re: How Important Is the Offset (ET) of a Wheel During Wheel Upgrade for Various Cars

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Originally Posted by lancer_rit View Post
Thanks. If you post your car's alloy wheel and tyre size, I could give some hints on a good setup :-)
Good luck.
I am hunting for 5.5JJ x14" alloys with new 185/70/R14 tubeless tyres. This setup would give me 2.5 mm added height and that's good for me.

The 5.5JJ x14" is the OEM specs on the top end Lancer SFX model but mine is the SLXi model that came with OE 5Jx13, ET=45 alloys, shod with the relic 175/80/R13 tubed Bridgestone tyres. I am still running on these and only 78K kms on the odo !!!

My hunt began 3 months ago, wanting to buy the same size tyres in tubeless but nobody makes that size in tubeless. The closest was 185/70/R13 which would reduce the GC by 13 mm and that was not acceptable to me. I have to drive in rural areas and the existing 185 mm GC helps a lot. Sometimes even this is inadequate when the roads are real bad. Thus a loss of 13 mm height with the 185/70/R13 is a strict no no.

Ok fine, I can live with tubed tyres (80 profile) but tyre companies have stopped making these as well. Bridgestone website still offers the S248 tubed tyres that suits me fine but nobody keeps stock of this size. Their zonal office could manage to locate only 3 tyres at three different dealers out of town and they won't commit fresh stock.

Thus started my quest for the 14" alloys and thus far I have not been able to get any decent 5.5JJx14 alloys. The events that followed were outright funny and at times frustrating.

I will continue later but can you conform the ET of the original 5.5JJx14 that came as OE on the SFX model?
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Old 21st September 2012, 13:19   #22
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Default Re: How Important Is the Offset (ET) of a Wheel During Wheel Upgrade for Various Cars

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Originally Posted by Chewbacca View Post
I will continue later but can you conform the ET of the original 5.5JJx14 that came as OE on the SFX model?
Here is a thought. I guess all variants of the Lancer had the same suspension set up? If so, then the wheels and tyres will be positioned exactly the same for all variants, and will have the same ET for both OE steel rims and OE alloys.

So, go ahead and examine the steel rim you have in the boot of your Lancer - the spare. The ET value should be stamped on it somewhere, is my guess.

And while you are doing the upgrade, why not go for 15" rims?

Last edited by KiloAlpha : 21st September 2012 at 13:20. Reason: clarity
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Old 21st September 2012, 14:14   #23
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Default Re: How Important Is the Offset (ET) of a Wheel During Wheel Upgrade for Various Cars

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Originally Posted by Chewbacca View Post
I am hunting for 5.5JJ x14" alloys with new 185/70/R14 tubeless tyres. This setup would give me 2.5 mm added height and that's good for me.

The 5.5JJ x14" is the OEM specs on the top end Lancer SFX model but mine is the SLXi model that came with OE 5Jx13, ET=45 alloys, shod with the relic 175/80/R13 tubed Bridgestone tyres. I am still running on these and only 78K kms on the odo !!!
The non-SFXi models have the better GC setup and the better OD. While SLXi/GLXi/LE had 185mm GC, SFXi has only 175mm. Please don't go by SFXi measurements.

For your Lancer, you can go to 5.5J*14 or 6J*14. No issues IIRC with JJ either (my wheels are JJ). Personally, I like 190/60R15, works great for me. But you can go for : 195/70R14, this is the same OD as Lancer 13" stock tyre combo.

Quote:
My hunt began 3 months ago, wanting to buy the same size tyres in tubeless but nobody makes that size in tubeless. The closest was 185/70/R13 which would reduce the GC by 13 mm and that was not acceptable to me. I have to drive in rural areas and the existing 185 mm GC helps a lot. Sometimes even this is inadequate when the roads are real bad. Thus a loss of 13 mm height with the 185/70/R13 is a strict no no.
With GC of 185mm stock, you'll have no problems. I drive on BLR mountain speed breakers :-)
You can find 195/70R14 in Michelin and other tyre manufacturers.

@Kiloalpha, the SFXi had a different OD than all other Lancers.

Last edited by lancer_rit : 21st September 2012 at 14:19.
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Old 21st September 2012, 14:40   #24
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Default Re: How Important Is the Offset (ET) of a Wheel During Wheel Upgrade for Various Cars

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Originally Posted by lancer_rit View Post
@Kiloalpha, the SFXi had a different OD than all other Lancers.
Alright, even with a different OD, would the ET be any different between wheels of the SFXi and GLXi/LE? That's what I was driving at.
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Old 21st September 2012, 14:49   #25
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Default Re: How Important Is the Offset (ET) of a Wheel During Wheel Upgrade for Various Cars

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Originally Posted by KiloAlpha View Post
Alright, even with a different OD, would the ET be any different between wheels of the SFXi and GLXi/LE? That's what I was driving at.
Ah, I misread your post a bit. ET can be same, but I can't remember that for sure. The user's manual list this IIRC.

For chewbacca, ET between 40-46mm is good. ET40 is good if going for 195mm.
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Old 21st September 2012, 20:15   #26
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Default Re: How Important Is the Offset (ET) of a Wheel During Wheel Upgrade for Various Cars

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Originally Posted by KiloAlpha View Post
So, go ahead and examine the steel rim you have in the boot of your Lancer - the spare. The ET value should be stamped on it somewhere, is my guess.

And while you are doing the upgrade, why not go for 15" rims?
My spare rim is also a 13" alloy.

15" would lower my tyre profile (to maintain the same OD) and as I said earlier, I frequently visit rural places so the reduced profile increases the risk of rim damage on bad roads.

Quote:
Originally Posted by lancer_rit View Post
For your Lancer, you can go to 5.5J*14 or 6J*14. No issues IIRC with JJ either (my wheels are JJ)
What is the difference between J and JJ?
I thought they put a double J when indicating a decimal

The first set of 14" Neo alloys that I purchased were 6J*14, ET=40 but I did not mount and check. My mistake. Later at the A*S*S they mounted one of them on the car and the inner rim edge almost touched the strut base. They promptly replaced it with the OE rim of another SFXi car. On that it was clearly mentioned 5.5J and was not fouling with any other part.

So I wanted the OE wheels of SFXi but they had none in stock. The list price is Rs 8500 each + taxes and they won't commit on fresh stock.

Quote:
Originally Posted by KiloAlpha View Post
Alright, even with a different OD, would the ET be any different between wheels of the SFXi and GLXi/LE? That's what I was driving at.
The ET will be different because of the 5J and 5.5 JJ (inches) difference.
Please correct me if I am wrong.
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Old 21st September 2012, 22:22   #27
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Default Re: How Important Is the Offset (ET) of a Wheel During Wheel Upgrade for Various Cars

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What is the difference between J and JJ?
I thought they put a double J when indicating a decimal
Not really. They are to do with the shape of the rim lip. Look here
http://www.carbibles.com/tyre_bible_pg4.html

BTW, last I had checked, J and JJ profiles are close enough that they work fine - one for the other.

Quote:
The first set of 14" Neo alloys that I purchased were 6J*14, ET=40 but I did not mount and check. My mistake. Later at the A*S*S they mounted one of them on the car and the inner rim edge almost touched the strut base.
Are you sure they were ET+40 ? I have 6.5JJ*15 ET+40 Hijoin H412 alloys, and nothing touches. Did you try to rotate steering wheel lock to lock and check ?

Quote:
They promptly replaced it with the OE rim of another SFXi car. On that it was clearly mentioned 5.5J and was not fouling with any other part.
If they put SFXi wheel on GLXi/SLXi/LX, then that messes up the GC, OD etc of the car as also the speedo accuracy.

Quote:
So I wanted the OE wheels of SFXi but they had none in stock. The list price is Rs 8500 each + taxes and they won't commit on fresh stock.
I recommend you try one or two other 5.5/6J*14 wheels and check the clearance after turning lock-to-lock. You can estimate clearance with tyres on the wheel ?

Quote:
The ET will be different because of the 5J and 5.5 JJ (inches) difference.
Please correct me if I am wrong.
That's not correct. J and JJ is about bead profile shape. It has nothing to do with ET which is the offset between vertical central plane of the wheel, and the hub mount plane. The shape of the bead profile can cause some issues with air sealing between J and JJ, wherein very slow air loss can happen - a psi or two in a month maybe.
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Old 21st September 2012, 22:53   #28
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Default Re: How Important Is the Offset (ET) of a Wheel During Wheel Upgrade for Various Cars

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Originally Posted by lancer_rit View Post
You can find 195/70R14 in Michelin and other tyre manufacturers.
Oops, 195/70R14 has a OD error of +3%. The correct upsize is 195/65R14, but this is not available easily. The other correct upsize is 185/70R14 which is available in Michelin and Bridgestone, for example.

I recommend 185/70R14.

Last edited by lancer_rit : 21st September 2012 at 23:01.
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Old 22nd September 2012, 00:34   #29
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Default Re: How Important Is the Offset (ET) of a Wheel During Wheel Upgrade for Various Cars

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I recommend 185/70R14.
Indeed, that what I am getting once the wheel deal is done. This size gives me 2.5 mm additonal GC .... more the merrier !!

Thanks for the link.
btw, I have found this excellent tool that compares tyre + wheel specs
http://www.rimsntires.com/specs.jsp
All variable parameters can be scaled in real-time and it also gives an approximation of the change in weight. too good.

Let me clarify about the fouling part. At the A*S*S, the car was put on the ramp and just one single NEO wheel was mounted without the tyres. I fouled big time and I could see it clearly.

Few things that I have noticed (nit picking) about alloys and is worth mentioning ...

1> Aftermarkets are all mostly 6J standard size. Dealer says it fits all.
2> Much much heavier than the OE Lancer wheel of same size. And to think of it, this is the rotating mass that gets doubled or triped depending on the speed !!!

3> Unacceptable weight deviation between wheels from the same set. (I weighed them on a digital weighing machine)
4> The wall thickness inside the sunk holes is sometimes scaringly thin (the place where the nut fits).

Anyway, tomorrow I am visiting MASS to check on Swift alloys. 4 brand new alloys are waiting for me @ 3300/- each and the storekeeper has assured me they are 14*5.5J with 100 PCD.

Wish me luck to get matching offset

Last edited by Chewbacca : 22nd September 2012 at 00:36.
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Old 22nd September 2012, 00:57   #30
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Default Re: How Important Is the Offset (ET) of a Wheel During Wheel Upgrade for Various Cars

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Originally Posted by Chewbacca View Post
Indeed, that what I am getting once the wheel deal is done. This size gives me 2.5 mm additonal GC .... more the merrier !!
2.5mm is good. My setup has 2mm extra :-)

Quote:
btw, I have found this excellent tool that compares tyre + wheel specs
http://www.rimsntires.com/specs.jsp
Thanks. Really good resource. Have seen one or two sites which are similar. The weights etc are only estimates though - shouldn't pay too much attention to that aspect.

Quote:
Let me clarify about the fouling part. At the A*S*S, the car was put on the ramp and just one single NEO wheel was mounted without the tyres. I fouled big time and I could see it clearly.
Well I have 6.5JJ*15, and they don't foul up at all. Not in 52k km over all kinds of terrain. And I have 195 section tyres on them. I am thinking if the smaller dia of 14" is the problem for your case ? Also, are you sure about the offset ? Was it +40 or ET40 (not -ve offset) ?

Quote:
Few things that I have noticed (nit picking) about alloys and is worth mentioning ...

1> Aftermarkets are all mostly 6J standard size. Dealer says it fits all.
It goes mainly with rim dia, and the kind of tyre width range folks would put. Typically, aftermarket alloys are atleast 0.5 to 1" wider for the same dia. It fits a wider range, not all. Look at Michelin website to see what are the min and max tyre widths that can be fitted on a wheel of 'x' inch dia.

Quote:
2> Much much heavier than the OE Lancer wheel of same size. And to think of it, this is the rotating mass that gets doubled or triped depending on the speed !!!
That will be true if OE wheels of the same size are alloys. OE alloys are of better materials, and much more expensive. It is also true if you take a 13*5J steel rim and compare to a 15*6.5JJ alloy rim. Unladen weight is ~10x laden weight IIRC.

Quote:
3> Unacceptable weight deviation between wheels from the same set. (I weighed them on a digital weighing machine)
That is surprising. What was the variation like ? Good quality Taiwan alloys should be consistent. My wheels, I made some rough checks - seemed similar weight - haven't weighed on a digital scale!
Quote:
4> The wall thickness inside the sunk holes is sometimes scaringly thin (the place where the nut fits).
Not the case in the alloys I bought, but I see what you mean. Manufacturing precision is not good for some of these alloys.

Quote:
Anyway, tomorrow I am visiting MASS to check on Swift alloys. 4 brand new alloys are waiting for me @ 3300/- each and the storekeeper has assured me they are 14*5.5J with 100 PCD.
good luck with matching offset!

Last edited by lancer_rit : 22nd September 2012 at 01:00.
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