305/30/20 Pilot Supersport rub - alternatives?

[Champale]

Hey guys,

Having some rub with my current setup. I have a 2013 Boss 302 LS on KW coilovers. Bought some HRE FF01s in 20x10.5 ET45 all around with 285/30/20 front and 305/30/20 rear Michelin Pilot Supersports.

The car is not slammed like K springs, but it is lower than my Ps were and I am getting a slight but noticeable rub on the rears (rubber on the inside of the fender lip and wear on the tire where the tread meets the sidewall).

So my question is this: has anyone ever had a wheel machined to increase the offset (i.e. taking my wheels and having the offset increased from 45 to say 50 or 52mm so that the tires sit inside the fender a little more)?

Or do I need to bite the bullet and buy narrower tires? I guess I could stay with the PSS and go down to a 295/30/20 or the 295/35/20?

Any input/experience would be appreciated. Thank you.

John

 

[Pentalab]

Hey guys,

Having some rub with my current setup. I have a 2013 Boss 302 LS on KW coilovers. Bought some HRE FF01s in 20x10.5 ET45 all around with 285/30/20 front and 305/30/20 rear Michelin Pilot Supersports.

The car is not slammed like K springs, but it is lower than my Ps were and I am getting a slight but noticeable rub on the rears (rubber on the inside of the fender lip and wear on the tire where the tread meets the sidewall).

So my question is this: has anyone ever had a wheel machined to increase the offset (i.e. taking my wheels and having the offset increased from 45 to say 50 or 52mm so that the tires sit inside the fender a little more)?

Or do I need to bite the bullet and buy narrower tires? I guess I could stay with the PSS and go down to a 295/30/20 or the 295/35/20?

Any input/experience would be appreciated. Thank you.

John

A 305-30-20 is aprx 27.2" diam..so it's not a tall tire. A 10.5" rim should have a 51.35 mm offset if you factor in the typ 10" rim with 45mm offset vs 10.5" rim. That extra .5" width = 12.7mm. 12.7 /2 =6.35mm . 45 + 6.35mm = 51.35 new offset....or round it up to 52 mm.

Never seen it done b4, but machining 6.35mm ( 1/4" ) off the back side of a rim is asking for trbl. As is, you would have to be really low on the back to hit the fender lip. The 295 tire will dump 5mm per side, so it might just work.

The 295-30-20 = 26.73" diam. 295-35-20 = 28.13" diam.
The 295-35-20 is taller than your existing 305-30-20 (by .93")...so although it's narrower than the 305, it's also taller at the tire / wheel well interface ( by .93" /2 = .465")

 

[Champale]

Hey Pentalab - thank you for your input. I have done the same calculations and come to basically the same conclusion you have. I would prefer not to machine the wheels if possible, but I have sent an email to the vendor to get some feedback because that might be the easiest/cheapest option.

I am not opposed to going to the 295 but have been very pleased with the very neutral handling characteristics I currently have am really don't want to mess with tire sizes.

 

[Norm Peterson]

With the cornering forces that a Boss LS can generate, I'm a lot nervous about machining the wheel's mounting pad by that much. Having a lugnut or two tear through their hole(s) in a fast corner would make for a pretty bad day.

Wheel mfrs do have to do some engineering and/or testing unless they're flat-out copying somebody else's wheel dimensions . . . all of them. If you're really lucky, these wheels might have a little extra margin (but at this point I wouldn't count too heavily on that being the case).


I'm assuming that sheetmetal mods are out of the question, at least for now.

Can you swap a pair of slightly stiffer rear springs in and dial the ride height up a little? If you can adjust the bump damping up a little without screwing with the handling too badly (might have to tweak the fronts as a consequence), that might buy you a little more breathing room.

Going to 295/30-20's will buy you about 0.15" on the radius (vertical clearance) and 0.1" laterally.


Norm

 

[DRock]

I have seen and heard of numerous people shaving mearly a couple mm's. Most shops wont do over 3mm. BTW picks?

 

[blacksunshine01]

If you do end up going 295 all the way around why not just run a square size if the wheels are allready the same?

 

[Champale]

Thank you for the replies. I am in contact with the vendor who has been very helpful (although he told me that the 305 would work and is surprised it rubs).

Why not square? Might be a possibility (I ran square 19x10s with 285/35 RE11s). Still would prefer to have a little more tire in back because the handling of the car is very neutral right now, oversteer is very predictable.

Not really inclined to add stiffer springs and/or more ride height because, like I mentioned, the handling setup is the best it's ever been. Might have to go back down to 19s and 285/35 + 305/35 PSS combo on wheels with correct offsets.

 

[Norm Peterson]

The actual contour of different tires can be enough to matter. Hard to believe that just within the Michelin PSS line the tread width of the 265/40-18 is within 0.1" of the tread width of the 285/35-18 (and the extra shoulder "thickness" on the 265's is readily noticeable with the tires just sitting there in stacks). Your seller may have checked clearance with somebody else's 305/30-20's (Nitto NT05's?) and assumed that all 305/30-20's would measure up the same.


Norm

 

[Champale]

Yes you are right, Norm. I probably should start a thread entitled "20x10.5 ET45 plus Michelin PSS 295s - any rubbing?"