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Discussion Starter · #1 ·
I am pretty sure there won't be any search results for this exact question, so here it goes...

Say you have a person with a tC with a big brake kit out front, sitting on TRD springs. With 18x8.5 +40 wheels shod with 225/40-18 tires (yes, this is an absolutely horrible matching of tire-to-rim width), the car is occasionally rubbing at the outer sidewalls and after about 500 miles, a groove about 1mm deep has been dug along the text on the tires. Would this be considered minor rubbing, or is this more like severe rubbing? The rubbing is noticeable my by sound and vision (looking at the tires) than by feel through the steering.

Anyhow, because of the rubbing, the owner of the car has switched to 17x7.0 +35 wheels shod with stock size tires and is experiencing zero rub; in fact, rubbing isn't even remotely possible in this configuration; the 1.5" narrower wheel plus 10mm narrower tire series is more than enough to offset the 5mm decrease in offset without rubbing.

Now, if that person were to switch to 17x8.0 +48 wheels shod with 245/40-17 tires, would he be rubbing again? Unfortunately, the amount of negative offset as a result of the brackets for the big brake kits is not a specific known figure, but it was enough to cause a problem for 8.5" rims shod with 225s and lowered 1.25" from stock.

Thanks in advance to anyone who is willing to help me out with this; my apologies in advance to those who think I'm wasting their time or should have somehow utilized the search function to better serve me in solving this particular problem.

-Ed

PS Yes, that's basically me and yes, I am seriously considering 245s for some time next year, and I know at least two wheels that come in 17x8.0 +48 that I'm happy with the styling and weight of, but I just cannot go through another rubbing fiasco, no way.
 

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You got a chance there, Ed. I mean 245s with 17x8 / 48 offset. No guarantees, though.
 

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17 x 8, not 8.5, in a +48 might be close. It will depend entirely on how much the brakes increase the need for offset. Like zoltiz says, you got a chance, but no guarantees at all. If the brakes add less than 6mm, it will work. If it's more, it probably won't work. I wouldn't even try it with 8.5 rims.
 

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Discussion Starter · #4 ·
So the rim width affects how far the sidewalls come out more than the actually tread width rating, I take it (which I was suspecting all along)...

The brackets for the big brake kit easily go past six mm; I'm guessing more like 10 to 15mm. This would explain why I was rubbing with 225s stretched over 8.5" rims.

I need to see what else I can try, and I don't mean rolling fenders and/or installing flares or widebody...

Thanks for your help, guys!

-Ed
 

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It isn't the brackets. They don't affect offset. It's the thickness of the hats and/or any spacers that were installed on the hub to help fit the brakes.
 

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Discussion Starter · #6 ·
Originally posted by lo bux racer@Oct 28 2005, 06:56 PM
It isn't the brackets.  They don't affect offset.  It's the thickness of the hats and/or any spacers that were installed on the hub to help fit the brakes.
That's what I mean by the brackets for the brakes; it's the bracket that is used for mounting the calipers farther out from the axle due to the size of the rotors. The billet hat is actually a bit thinner than the center portion of the solid iron stock rotors (Actually, I need to measure this to verify, come to think of it...).

The stock wheels have fairly thick, absolutely straight spokes and a +45 offset, and still clear the outside of the calipers by two to three mm; I wonder if I could get away with a wheel with curvier, thinner spokes in a +50 offset...

-Ed

EDIT: I need to see if there are spacers involved besides the hat and bracket; thanks for the reminder!
 

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Discussion Starter · #7 ·
My apologies, Lance; you're right--the brackets don't matter.

Here's a link to the directions and diagram of the kit.

-Ed

EDIT: Hey it inidcates .3" hat thickness reference. That's thinner than the stock rotors as I suspected--wtf? And the diagram shows no spacers!
 

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OK, the new hat is 7.6 mm thick compared to stock, which is 6.39 mm thick. So you've got 1.2 mm additional track. A 17 x 8 with a +48 offset should work just fine.

(No, I didn't pull that number out of my a55, I took off my front wheel and measured it.)
 

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Discussion Starter · #9 ·
Originally posted by lo bux racer@Oct 28 2005, 08:02 PM
OK, the new hat is 7.6 mm thick compared to stock, which is 6.39 mm thick. So you've got 1.2 mm additional track. A 17 x 8 with a +48 offset should work just fine.

(No, I didn't pull that number out of my a55, I took off my front wheel and measured it.)
Lance now I owe you a beer; I wish I weren't three time zones away. Seriously; who takes off their wheel (risking scratches to their wheels/lugs in the process) to measure the thickness of a brake rotor for some guy on a forum?

Sheesh, I owe you!


-Ed
 

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Originally posted by lo bux racer@Oct 28 2005, 08:02 PM
(No, I didn't pull that number out of my a55, I took off my front wheel and measured it.)
another example of how thorough lance is in his work...

good job! ill have to keep that in mind when i move to new rims and 240 or 245 wide tires...

p.s. what is a good size rim for 240/245s and a good manufacturer that has some choice for those... that might be my next purchase before i get coilovers & strut bars...
 

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Discussion Starter · #12 ·
I'm personally looking at either 5Zigen FN01R-C or Enkei RP03, both come in 17x8.0 +48 and offer convincing colors/finishes, and I'm fairly satisfied with how they look (not as happy with how they look as I am with the ones I have, but these don't come in that size & offset). I'd be doing 245/40-17 size tires on these wheels.

-Ed
 

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Either of those are an excellent choice. I was seriously thinking about them for the wife's car until she reminded me of how I chewed her ear about scratching the rims on both my car and hers. She's getting OEM size tires on the OEM rims, just better tires (tomorrow!), as long as I can find T1Ss or T1Rs. They'll definitely be better than the RE92s.
 

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Discussion Starter · #15 ·
Originally posted by josurr@Oct 28 2005, 08:24 PM
thx ed...

do you know what rubber would be great/awesome to wrap those in?
I've never really compared enough summer tires to really know the answer to your question myself (there's a nice tire review thread for that, actually), but Tire Rack's recommendation of the Avon Tech M550 has me very satisfied (actually one of the reviews in that thread I just mentioned), so I am not afraid to go with their recommendation for summer tire, either.

-Ed
 

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Discussion Starter · #17 ·
5x100 is the lug pattern, and that is the correct lug pattern for Scion tC's hubs.

17x8.0 +48 is the correct size & offset to pull off 245s as per our discussion here with stock brakes and suspension.

-Ed
 

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Enkei RP03

good/bad price? also what tires should i get with these rims? i was thinking the pirelli's, but it would take a while to get the $2k it costs for the set..

should i just go with the rims and tires separately? any good places to buy the RP03 for cheap and a solid gripping tire with a good tread life for cheap as well?

im up for suggestions for both (esp. with the tire maker & type)
 

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Originally posted by josurr@Oct 28 2005, 09:22 PM
Enkei RP03

good/bad price? also what tires should i get with these rims? i was thinking the pirelli's, but it would take a while to get the $2k it costs for the set..

should i just go with the rims and tires separately? any good places to buy the RP03 for cheap and a solid gripping tire with a good tread life for cheap as well?

im up for suggestions for both (esp. with the tire maker & type)
While 17.2 pounds for a 17x8 wheel is respectable, the $360 or so per wheel is staggering. they don't specifically mention the wheel being forged, so I can't see what the cost is for. If I take a strong blow to the head and decide to pay $350+ a wheel, I'm getting full-on forged racing wheels, with full-on shaved racing tires. Then the rampaging will begin.
 
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