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Old 11-29-2004, 12:34 PM   #1
engineerx
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Default +44 offset detrimental to steering?

I tried the search, but could not find any info:

I'd like to know if anyone has experienced adverse effects from using 17x8.5 +44 or 18x8.5 +44 wheels.

I like the Volk CE28N for my STi and I want the widest wheels possible, however I'm hesitant to buy them because of the offset issue. If I use +44 on a 8.5" wide wheel I would not like to have the steering geometry changed so much that it would cause noticeable steering effects. I'm using the Rev-Lab 12.5:1 steering rack and TEIN RA's and go to the track often... so that's important!

I know that in order to fit the 8.5" wheels, the +44 offset is necessary so they won't rub the shocks....

Also, is it possible to have different offset in the front (different from the rear)?
if there is more clearance in the front suspension and the rear geometry is the limiting factor for wheel offset, then I'd rather have a closer to OEM wheel offset in the front

Has anyone experienced any steering issues with these wheels? Any STi owners using them?

Thanks for your input!
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Last edited by engineerx; 11-29-2004 at 02:49 PM.
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Old 11-29-2004, 02:57 PM   #2
keyser_soze
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i have CE28N 18x8.8 47 offset 5x114.3 w/ 225/40/18 t1-s . no problems. I just have Tein S-Tech springs, only thing the spokes are 0.0000000000000001 mm away from the calipers in the front ....but don't touch....good luck!

i was worried...in hard cornering if the spokes flex they would tocuh the calipers but it hasn't happened yet...so i think i'm ok
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Old 11-29-2004, 04:27 PM   #3
engineerx
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wow! that's cutting it close !!

Problem is Volk has limited wheel sizing for PCD 100 !
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Old 11-29-2004, 08:03 PM   #4
Chunky_Chicken
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Changing offset changes your scrub radius. If you were to make a line between your upper damper mount (top hat) through your lower ball joint into the ground and then measure the distance (in the lateral direction) between where that point intersects the ground plane to where the centre of area is for your tire contact patch you would have your scrub radius.

Since your suspension geometry doesn't change when you change wheels, but your contact patch moves away from the centre of your car when you reduce wheel offset, you are essentially changing your scrub radius.

Changes in scrub radius are percieved as changes in steering efforts and road/tire feedback.

I run stock offset 17" wheels in the summer for street, race on 45mm offset wheels, and rally in 35mm offset wheels. I can instantly tell the difference even just static steering at a stop.

The more you reduce offset, the 'lighter' the steering feels. But, the more you reduce offset the more longitudinal inputs are transmitted through the contact patch and are felt in the steering.

For instance, with my 35mm rally wheels I would say my overall steering efforts are about 25% less. The car feels more responsive and more 'tossable'. Under braking, if one wheel locks I instantly feel it through the wheel. When I dip my inside front tire into a ditch and tag something hard I feel it immediately, even the slightest hit.

The jacking effect you mildly get with stock geometry due to dynamic camber gain from high castor is exaggerated. The car kinda feels like it carves turns.

Personally, I like the feedback I get running low offset, and I would do it year round if it didn't already cost me a set of wheel bearings every 18 months.

Be carefull with your quick rack. The low offset will make the car even more twitchy, and the feedback through the wheel given the lower ratio will be somewhat muted.

Just a heads up, but if I were you I'd do it. 44mm offset isn't going to kill your bearings immediately, but it will affect their lifespan. Consider them a consumable like tires and its not hard to justify (well at least in my twisted mind! )

-Pete
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Old 11-30-2004, 01:33 AM   #5
engineerx
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Pete - thanks for your write up ! - and taking the time to answer my question.

Now I see what the effect would be and can make a more educated decision.
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