S6 C5 tyre sizes..
10-05-2011, 03:46 PM
#21
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10-06-2011, 06:24 AM
#24
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Now i'm lost. We first need to sum the effects of the wheel offset and the spacers to get a nut effective offset. Stock is 35mm. As you go lower, you are in effect pushing the wheel out on a lever arm. Do the math. By the time you are at ET15, you are 20 mm, or 8/10ths of an inch, out. That's a lot of scrub radius, torque on the wheel bearing, and leverage on the suspension. I*'d warrant the first two are the most important.
You can clear 255s with stock offset and +2.5% rolling circumference, so i fail to see the need to pimp them out so far.
Is that clear?
G
You can clear 255s with stock offset and +2.5% rolling circumference, so i fail to see the need to pimp them out so far.
Is that clear?
G
10-06-2011, 06:33 AM
#25
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As I recall, it was about OP wanting to run a certain wheel that would not clear the front calipers without spacers, so in order to run those wheels, the spacers are necessary.
I'd be surprised if leverage on the wheel bearing were an important consideration, but changes in scrub radius, caster jacking, and roll center (i believe that's the correct term) *could* at worst make the car drive dangerously and unpredictably, and at best make the car handle differently from intended.
Porsche 928 guys routinely run 1-2" spacers, so I won't be so absolute as to say spacers are always bad; you just have to be cognizant of the effects they have on the dynamics of the car.
How about sticking the wheels on a rotor lathe and clearancing the spokes? :-) I've thought about doing that with my fat fives and avus wheels to make them lighter for the drag strip.
I'd be surprised if leverage on the wheel bearing were an important consideration, but changes in scrub radius, caster jacking, and roll center (i believe that's the correct term) *could* at worst make the car drive dangerously and unpredictably, and at best make the car handle differently from intended.
Porsche 928 guys routinely run 1-2" spacers, so I won't be so absolute as to say spacers are always bad; you just have to be cognizant of the effects they have on the dynamics of the car.
How about sticking the wheels on a rotor lathe and clearancing the spokes? :-) I've thought about doing that with my fat fives and avus wheels to make them lighter for the drag strip.
10-06-2011, 07:14 AM
#27
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to "fill the wheelwell better" you would do better to lower the car another 1/2" rather than increase the tire size. This also reduces you clearance issues. Which in turn allows you to get back to a near-stock offset and suspension geometry. target 30-40mm. Since oyu want wheel clearance, closer to 35-30 likely. 15 is a bit much.
G
G
10-06-2011, 08:28 AM
#28
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generally agree. But i still want clarity on the offset of the original wheel; the spacer, the net (A+B) and why, if true, a wheel of proper offset has interference problems with the right (i get spoke variations for calipers, but that's not his issue).
Rear drive cars are generally more forgiving of offset changes, and Porsches have significant caster which helps.
Spacers, no matter how you cut it, create both a second mating surface and a second centering variation. they are in always inferior to a wheel of proper offset int he first place.
As to the force on the wheel bearing. Maybe yes, maybe no. But let's say the designed in distance from the center of the WB to the center of the tire is, say 4". Now you make it 4.8" (4" + 20mm). Your torque just went up by 20%. You decide if that is significant. Its 20% though!
G
Rear drive cars are generally more forgiving of offset changes, and Porsches have significant caster which helps.
Spacers, no matter how you cut it, create both a second mating surface and a second centering variation. they are in always inferior to a wheel of proper offset int he first place.
As to the force on the wheel bearing. Maybe yes, maybe no. But let's say the designed in distance from the center of the WB to the center of the tire is, say 4". Now you make it 4.8" (4" + 20mm). Your torque just went up by 20%. You decide if that is significant. Its 20% though!
G
10-06-2011, 12:17 PM
#29
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Now you've jumped on the 'pimping' bandwagon too although your pimping reference is to spacers rather than 4driver4's opinion that increasing the tyre diameter by an inch is the definition of pimping..
Not sure how it's not clear to anybody reading this thread, I have a situation created by the previous owner of the car, it is not of my making, it is historic, it is in the past tense, hence my comment about not wishing to pimp my ride. If I need to change the wheels or get them machined to correct what in your opinion or by popular consensus is an unsatisfactory set up, I will.
Your input is appreciated but please don't tell me I'm pimping my ride, because I'm not, it may have been pimped but not by me..
I will take one of the wheels off at the weekend and see what the actual ET is as so far I've only measured the set up which may easily be 5mm - 10mm out.
Thank you all.
10-06-2011, 02:01 PM
#30
I think that the reason why I, in your opinion, 'dissed' 4driver4 was that I didn't feel his original comment was relevant to the thread. I also think, judging by his second response, he's confident enough in himself and his position here not to have taken offence at my comments.
But thanks for sticking up for me, G.