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Re: 215 Tires: where do they rub?

To: 6pack@autox.team.net
Subject: Re: 215 Tires: where do they rub?
From: "Robert M. Lang" <lang@isis.mit.edu>
Date: Mon, 1 Aug 2005 17:46:27 -0400 (EDT)
On Mon, 1 Aug 2005, Tomislav Marincic wrote:

> Thanks to everyone who answered my question about 16" Panasports. The
> concensus was they might rub a little with 215 width tires.

You can eliminate any rubbing with wheel spacers, sometimes 1/4" will
work, sometimes you need a tad more. If you go to really thick spacers
(more than 3/8"), then the stock studs are too short and you need to
change them for longer studs. Also note that the center sections for some
wheels are "thicker" than others - this effects whether you can use
the stock studs or not.
 
> Can anyone tell me where the rubbing occurs: front or back, brake side
> or lugnut side. My body is off the frame at the moment, so rolling or
> grinding the outer fender lips would be relatively easy: is this of
> any value?

The rubbing can occur on:

Front Suspension:

1. the front sway bar. This only happens at full lock with really wide
tires (225's or 9 inch cantalever slicks). The solution is to change the
wheel stop on the trunnion for a slightly larger diameter. Trust me - you
NEVER need full steering lock on a TR6, so this operation has no impact on
the drivability of the car.

2. the upper a-arms - again, only at full lock. This only effects tires
that protrude beyond the wheel. So 9" cantalever slicks will do this with
15" wheels. 16" wheels should clear the upper a-arm totally.

3. fender lips - only at full lock _AND_ full suspension compression on
lowered cars. You can tune this out by modifying the bump stops on the
shock by making them slightly longer. The upper bump stop on the TR6 front
suspension is a sleeve on the shock shaft. You MIGHT be able to get away
with changing the bump stop material to something harder (like poly
urethane), but I have not tried that. Others can chim in on this one.

Rear Suspension

1. Upper bump stop perch - With the stock wheel offset, there's a chance
that the inside of the tire will rub on the upper bump stop perch. You can
modify the perch with a 3 lb hammer or you can add a small spacer to move
the wheel out.

2. trailing arm - the inner sidewall of the tire can rub on the trailing
arm. The fix is to add a spacer. Period. I can only seen this happen with
cantalever slicks and 225/50-15's mounted on 5.5" rims.

3. fender - no rubbing except in extreme lowering jobs. You can tune
arouns this with mods to the upper bump stops - but be prepared for some
intersting handling if you like to "chuck" you cars into corners. Can you
say "oversteer"?  =:-0
 
> Bob Lang, I know you auto-x with 16" Panas, can you offer any advice?

I do not use 16" wheels. My current rules limit me to 15X7 rims. I run
15X7 panasport lights with Goodyear 23 x 9 x 15 slicks. These tires stick
out a full INCH from the rim and therefore are probably the worst case
when it comes to interference problems.

My current setup has 15 x 7 Panasports with ZERO offset. I need to run
3/4" spacers in the front, so theoretically you could get your wheels set
up with 3/4" negative offest (which is 18 - 20 mm), but you only need this
if you are running cantalever tires.

When the rules change, I get to buy 16's (or whatever) and then tires that
cost $300+ each (as opposed to the $200 tires I get now). Yippee!

> I finally went with 215/60/16 Michelins. I didn't want 215 width, but
> by going wider I could get a lot more tire choices. 215/60/16 Michelin
> XGT H4's show a 26.3" installed diameter at the Tire Rack, which is
> close enough to the 26 7/8" of my old Michelin Redlines (worn).

Sounds like a reasonable choice. I once calculated that 225/60-16's are
the same diameter as the 185-15 stock tire height. 

One way or the other, the 16 inch rims get you in the ballpark for some
better "performance" tires such as the 60 series.

> Thanks,
> 
> Tomislav Marincic
> tomislav.marincic@earthlink.net

regards,
rml
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