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Old 01-18-2006, 12:07 AM   #1
subber
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Post 245-40-17 Impressions and Questions

I drive an 04 WRX sedan. I installed a set of 17x8 Rota G-Force with 245-40-17 Michelin Pilot Sports. I've been running this set for 2 weeks now. First thing I noticed is the loud noise, stiff ride, and heavy, numb steering. The last one proving to be the most disturbing.

The plus side is dramatically improved cornering grip, and quicker, more precise steering response. There's also somewhat improved acceleration, perhaps due to slightly less rolling diameter. And (I have to admit) the subby looks so much better -- it's sick!!

The downside is the loss of steering feel. The steering effort is also so much heavier. It feels like I'm driving a much bigger, heavier car. The steering feel is no longer light and delicate which I now realize I liked a lot. I can live with the noise and the stiffer ride. I was expecting some degradation in steering feel but I didn't realize it will be this much.

What do you guys think the biggest contributor to the difference in steering? Some of my questions:

1. It could simply be the extra width. If this is the case, it can perhaps be fixed by going with narrower tires -- 225-45-17. Even on parking lot speeds, steering is heavy. Any opinions?

2. Could it be the grippier tire?

3. Would 225s look stretched on an 8" wide rim? Anybody got any pictures? By stretched, I mean the wheel lips protruding far out from the tire treads.


My previous setup was 225-50-16 Michelin PE2 on stock 04 wheels. This setup is quiet, good ride, and nice, delicate steering feel. However, it does not handle and grip the road as well as the bigger tire setup. Please help me.. your opinions are very welcome.

Some pics:



My tires:
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Old 01-18-2006, 12:44 AM   #2
nhluhr
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Quote:
Originally Posted by subber
I drive an 04 WRX sedan. I installed a set of 17x8 Rota G-Force with 245-40-17 Michelin Pilot Sports. I've been running this set for 2 weeks now. First thing I noticed is the loud noise, stiff ride, and heavy, numb steering. The last one proving to be the most disturbing.

The downside is the loss of steering feel. The steering effort is also so much heavier. It feels like I'm driving a much bigger, heavier car. The steering feel is no longer light and delicate which I now realize I liked a lot. I can live with the noise and the stiffer ride. I was expecting some degradation in steering feel but I didn't realize it will be this much.

What do you guys think the biggest contributor to the difference in steering?
MOST of the heavier steering feel is a result of the lower offset. Rota's are +48 and stock are +53 (or +55 on some production runs). This causes a positive scrub radius, which, in english, means the center of the tire is no longer underneath the pivot-point of the steering. So instead of the tire pivoting cleaning around the pivot-point, it is now "wiping" around it. Effectively, you're swinging the tire to turn instead of spinning it in one spot.

Of course, stickier rubber also contributes, but it's mostly the scrub radius.
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Old 01-18-2006, 08:26 AM   #3
Bundyboyz
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I'm running a 225 45 17 on an 8 inch wide wheel... it's an 03 wrx stock suspension... I had no clue I could run a 245... You have no rubbing issues?
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Old 01-18-2006, 08:56 AM   #4
Jim Lewis
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How can you have both "numb steering" and "more precise steering response"?

Just wondering. I'm installing a set of RE070 (STi takeoffs) next week, but since I have 8" wide wheels, my next tires will be 235/40s or 245/40s. Looks great, less filling, etc.
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Old 01-18-2006, 05:00 PM   #5
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Quote:
Originally Posted by Jim Lewis
How can you have both "numb steering" and "more precise steering response"?

Just wondering. I'm installing a set of RE070 (STi takeoffs) next week, but since I have 8" wide wheels, my next tires will be 235/40s or 245/40s. Looks great, less filling, etc.
Your RE70s are as wide or wider than some 235s.
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Old 01-18-2006, 09:16 PM   #6
subber
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Quote:
Originally Posted by Jim Lewis
How can you have both "numb steering" and "more precise steering response"?

Just wondering. I'm installing a set of RE070 (STi takeoffs) next week, but since I have 8" wide wheels, my next tires will be 235/40s or 245/40s. Looks great, less filling, etc.
I guess that can sound a bit confusing. By precise steering, I mean I can place the car pretty much where I want to. I also mean that the car can hold a line more tightly like when going a round a bend at high speed, the car stays on my intended arc without as much steering correction. By "numb steering", I mean less feedback from the tires. I don't feel as much road surface feel on my fingertips.

I think the Michelin Pilot Sport version of the 245 tires are skinnier than 245 tires from other makes. In fact it seems to be just as wide as the RE070s once mounted on 8" rims.

I got no rubbing issues.. I'm also running eibach prokits on stock struts.
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Old 01-18-2006, 09:20 PM   #7
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I'm glad to hear you don't have any rubbing. I have eibach springs and 245/35s on the way

Gonna roll the fender anyway.
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Old 01-18-2006, 09:21 PM   #8
subber
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Quote:
Originally Posted by nhluhr
MOST of the heavier steering feel is a result of the lower offset. Rota's are +48 and stock are +53 (or +55 on some production runs). This causes a positive scrub radius, which, in english, means the center of the tire is no longer underneath the pivot-point of the steering. So instead of the tire pivoting cleaning around the pivot-point, it is now "wiping" around it. Effectively, you're swinging the tire to turn instead of spinning it in one spot.

Of course, stickier rubber also contributes, but it's mostly the scrub radius.
I was afraid this might be the cause. Which can only be fixed by changing to rims with correct offset.. but I love the looks of these rims..

There's only 5mm difference between stock offset and the Rotas, is that truly enough to make the steering so much heavier? That's less than a quarter inch...
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Old 01-18-2006, 09:23 PM   #9
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Quote:
Originally Posted by waktasz
I'm glad to hear you don't have any rubbing. I have eibach springs and 245/35s on the way

Gonna roll the fender anyway.
Cool! What size tires/wheels are you currently running? Let us know if you have the same experience about steering feel..
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Old 01-18-2006, 09:25 PM   #10
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yes, but going from 0 scrub radius to 5mm scrub radius is an infinity% increase

I will say that the vast majority of people are not bothered by this and even further, the majority of people don't even notice this.
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Old 01-18-2006, 09:25 PM   #11
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I have 225/45-17s on +50 wheels as my winter set...and havn't been on stock tires since 500 miles on my car so I can't really compare.

When my 245s and 17x8 +48s show up, I'll let you know Should be this week, although edgeracing hasn't changed my card yet so I doubt they shipped.
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Old 02-02-2007, 01:40 AM   #12
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To note. If you want precise response when you move the steering wheel. For instance being set up for autocross. Like Big sway bar with endlinks and stiffer bushings along with steering rack bushings. You can have a twitchy ride that reacts to every bump on the rode.

Steering rack bushings are only what $30. There are lots of mods to help with this.
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Old 02-02-2007, 01:41 AM   #13
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I am currently running 255/40/18 Michelin Pilot Sports front.

Suspension is not stock. So far love these things. Tons of grip.
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