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The mkiv Supra Owners Club

new 18 inch wheels - scraping arches a little


roboldham

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Hi folks

 

I just got some TRD alloys of another board member.

 

We have been racking our brains because the rears are scraping the inner wheel arches over heavy bumps in the road.

 

It's okay 95% of the time but its always there at the back of my head - taking the edge off some driving experiences.

 

I have rolled the arches in as tightly as we can get them - but still I get the odd little scrape when going quick or over slight bumps under heavy load to one side (especially if I have a passenger)

 

Rears - 285 30 ZR 18s

 

The offsets should be perfect for the car - they are TRD.

 

The left rear camber is slightly greater than the right - and the right catches more frequently.

 

When the old wheels came off (Jspec 16 inchers) the left rear wheel was virtually bald on the inside. Could be camber, could also be toe / tracking.

 

Any advice - should this be happening at all - I haven't read of anyone elses 18's scraping the arches in this way.

 

The car's handling is still very good so I know the wheels are right - just this damn scrape.

 

Thanks a lot for any help!

 

R

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Guest Martin F
Originally posted by roboldham

The offsets should be perfect for the car - they are TRD.

 

 

That doesn't mean anything, they could be for a Celica, Corolla or even a Yaris.

 

What offset are they ?

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Hi roboldham,

 

well seeing as your tyres are 18 285/30 then i guess your rims width is around 10.5 - 11" correct?!?!

 

if so then you need an offset of at least 48 mm wo miss the inner arches - and smaller and you will grind the top most part of the inner arch as the suspension cambers more under load.

 

I have an Excel spread sheet *see attached zip file* i was emailed a while ago when i was looking for my wheels - its very accurate too, try playing with a few values, you may just need to add spacers of like a few mm or so?!?!

 

Hope this helps!!?!?!? :thumbs:

 

L8r

 

rooster

:flame Dev

supra wheels fitment.zip

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Thanks for that file - looks useful, all I gotta do is understand it now.

 

I got 10.5"s on the rear.

 

What's the best way of obtaining the offset just by looking at the wheels?

 

I am waiting for the original owner to get back to me in the meantime - it is gone midnight admitedly :-)

 

R

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hi robo,

 

Yeah that sheet is cool!! - it look over complicated but gives a few examples for you - you just need to enter your tyre/wheel info in to the area marked "input your info here"

 

I assumed your wheels would be 10.5" so basically the smallest offset you can have with 285/30 tyres is 48 - any smaller it'll scrub - really you want 50-52mm offsets to be in the clear - 55mm is as large as you can go or else you'll hit your outer arches!! :(

 

well unless you trim them *yukky* :eek:

 

normally the offset is on the inside of your alloys or near the rim as on the stock alloys!??!!

 

L8R

 

rooster

 

:flame Dev

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f*ck, I am a numbskull.

 

I just re-read my post and they are scraping the OUTER arches, where the little lip is.

 

They have both been rolled in and still I get the odd little scrape every now and again when getting fruity.

 

Sorry if I mislead anyone - I am a dunce.

 

Anyway - I shall obtain some more info on the wheels - I definitely dont need spacers as that would push them out even further!

 

I *think* the offset is 50 (mm?) - but waiting for confirmation

 

R

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Yar - this is doing my nut now!

 

I got these wheels cos I wanted to keep all the offsets the same as standard so I would keep the handling spot on but with more rubber.

 

So - I am hoping I can get this issue sorted, in my head and on the road.

 

Thanks for input chaps - I will get some more exact info on the alloys and return

 

R

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Guest Usmann A

Rob,

Whem me pops fitted 18s on the supra, with 275/35 the rear, outside arches, where the lip is under the arch would rub against the tyre sidewall, causing marks and damage on the tires.

Basically you might have to get some height adjustable suspension to raise the car, althought ours from Japan was very very low, and we raised it about 20mm, and set it harder so no more play, which causes it to stop rubbing.

So thats the only we overcame it, thier must other solutions which are less expensive then buying suspension, lucky in our case the car already had it.

 

 

Sorry not much help....but our experiences at least.

 

 

Kind Rgds

Usmann Ali

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I wonder if the VVTI has a different offset requirement.

 

I'm on stock suspension with 18x9.75" rears and 285 tyres which are actually too big as they are 285/35 (too tall) I've not had them rub. In fact there is plenty of space. I think mine have an ET of 50mm as well...

 

It's starting to sound like you might have to roll the arches a bit...but no one can really say without looking at the car in person.

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