How close is too close for a brake caliper

[1jz68u]

very true and he is just around the corner.

[wagonist]

Instead of starting a new thread, just thought I'd continue with this one.

How close is too close for a tyre to strut clearance?

The rears are a problem on my car.

Stock setup is 6" wide rim with a +39 offset.
Now running 7" wide rim on a +40 offset which is fine.

but i'm heading upto the WRC next weekend to service for someone & am not particularly keen on runnign the 17s over rough roads.

I've got a set of WRX rally rims (with rally tyres) I'd like to run, but they're a 6.5" rim with a +50 offset.

The rally tyre sidewalls are stiff as & there's about 3-4mm of clearance.

Thoughts?

[Mr.Phreak]

Is that clearance with the suspension at full extension?? Or is that with the car sitting on the ground??

[wagonist]

Doesn't matter, strut moves with the tyre.

It's the sideways clearance to the strut tower that I'm worried about. ie tyre flex over bumps, cornering, etc.

[dfunkt]

so you'll be going 6mm closer to the strut.

how much clearance is there currently?

[CrUZida]

My rim's are literally ~2mm from my struts, and likewise the tyres are about 0.5mm from the struts.
But the tyres are rubber, they'll just wear a little bit (its purely the gutter guard that is that close to the strut).

[wagonist]

^^^^ Crap

I've got a pic on my phone, but I can't get that onto the puter...

Got more clearance than that with the rally rims/tyres fitted.
The rally tyres are also only 185 wide, vs the current 215 tyres, and also have uber stiff sidewalls due to the terrain they're required to operate within.

Well, that's sold me. I'm just happy not to have to run spacers, the tyres are getting old and didn't cost me a lot, so I'm not too worried if they rub a little bit.
But damn they're noisy, but extremely grippy (on dirt).

Very worst case is that I'll fit the rally tyres to my stocky rims with the correct offset, but that involves extra cost for very little gain.

Thanks for the input.

[Cuzzo]

My corolla tyres where just as close if not close to pic above. They did rub slightly just polished the strut.

[JustenGT8]

5mm is fine....3-4mm is a good chance of touching but not badly. Just make sure there are no 'edges' that will cut the tyre

[o_man_ra23]

But the tyres are rubber, they'll just wear a little bit

Wrong. For proof of what rubber will do to steel when rubbing, have a look at the tailshaft yoke of any 70's Toyota, or the rear main seal surface of the crank, or the front main seal surface of the crank pulley. They were all flat when new. Rubber will wear through steel before you know it (many years of downhill riding on cheap bikes taught me that)

As for how much clearance is enough, well that depends on how much your bearings will move, how much the sidewalls will flex, how much the strut will flex, etc etc. Rule of thumb for a street vehicle is 10mm minimum clearance, though I am not sure if that extends to tyre-strut or not. I guess you will have to look at the shiny spot on your strut throughout the day and make sure it doesn't appear.

[CrUZida]

HARD rubber will wear through steel.
SOFT rubber will be worn away by steel.

The proof is the fact that my struts are not damaged (apart from the paint, and a light polish), the fact that the whole area is covered in little bits of rubber, and the fact that the tyre shows signs of contact

[takai]

Ive seen a 60A downhill tyre wear through a 4130 Cromo frame before. Trust me, it does happen.

[love ke70]

tyres that scrub on chassis' do more damage to the chassis than you notice on the tyre.
as its obviously a decent trip your going on, id be happier seeing them on the proper offset tyres, butttt, if it was my car, id probably run it as youve described...

[wagonist]

Struts are due for replacement anyway

1000k each way trip on non-new rally tyres, they'd be lucky to get there & back.
The sidewalls may be stiffened to buggery, but the rubber is as soft a track tyre. Generally designed to last 500km, tops.

Plus the stereo would have to be very loud to overcome the tyre noise (ever been in a 4wd with mud tyres)
Nope, they'll be hitching a ride in the cargo area up & back. Just don't trust 17s + low profile rubber at rally events

[love ke70]

i drive a 4wd with mud tyres daily, use an ipod not the stereo, it drowns the noise out better

which rally event? not the repco event in northern NSW? i was considerign making my way down to see that...