Holbert race car gets 305s up front with no body work (kind of)
12-04-2008, 03:19 PM
#31
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Thread Starter
Ill have to see if i can get the video clips on youtube.
mk
mk
If you ever drive a truck with 15 inch riims and big oversized offroad style tires the whole truck will float side to side as you go down the road as the rims move side to side relative to the tread with just minor steering corrections. The combination of tall soft sidewalls AND / \ pinched in at the the rim makes it feel really bad. And yes the GT3 911 is an amazing "street" car I instructed a student with one and loved the POWER ! As always I opted NOT to drive his car but I was very tempted just did not have a spare $150,000 to pay for it if I crashed it 
12-04-2008, 03:22 PM
#32
Former Vendor
12-04-2008, 06:19 PM
#33
Rennlist Member
I am interested in the idea of increasing front wheel/tire size to offset push understeer. The potential downside is decreased turn in, especially in low speed corners. To combat this we can run more neg and some toe out (although toe out is meant to be bad under high speed braking). So what's the magic formula?
12-04-2008, 07:44 PM
#34
Rennlist Member
Thread Starter
The car acted fine in the slowest of tight turns.
i cant say the car acted that much different. it was more of a feeling of too much tire,not gripping as it could, but near equal of the smaller tires.
Here is the street test before the track day.
http://www.youtube.com/watch?v=V2nmzFeWB0c
Here is the race video
http://www.youtube.com/watch?v=qGqSJkmCyb0
mk
i cant say the car acted that much different. it was more of a feeling of too much tire,not gripping as it could, but near equal of the smaller tires.
Here is the street test before the track day.
http://www.youtube.com/watch?v=V2nmzFeWB0c
Here is the race video
http://www.youtube.com/watch?v=qGqSJkmCyb0
mk
I am interested in the idea of increasing front wheel/tire size to offset push understeer. The potential downside is decreased turn in, especially in low speed corners. To combat this we can run more neg and some toe out (although toe out is meant to be bad under high speed braking). So what's the magic formula?
12-04-2008, 08:36 PM
#35
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Since Ed Ruiz no longer posts there has been little discussion of the contact patch Suffice it so say that wider tires have a contact patch that is wider and shorter which is better for side loads (corners) with less squirm/distortion of the tread and tends to run at lesser slip angles.
Suffice it so say that wider tires have a contact patch that is wider and shorter which is better for side loads (corners) with less squirm/distortion of the tread and tends to run at lesser slip angles.
12-04-2008, 11:39 PM
#37
What's the widest you could go in the front and the back by only rolling the fenders and no other mods? Could you do 295's in the front? How wide in the back? Thanks!
12-05-2008, 12:09 AM
#38
Administrator - "Tyson"
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I'll be copying this setup on my 79. It's not a setup I would use on the street for regular driving.
12-05-2008, 12:27 AM
#39
I'm just street driving, no track. I saw another thread where widening wheels was discussed. So I thought, what if I had my front tires widened in order to accomodate ridiculously wide tires (315+?) in the rear, and then put my current rear wheels in the front (I think they have 285's or 295's on them). Is that feasible? Goal would be to have wider tires for the supercharger plus I like the wide tire / bad *** car thing. (OK, 98% is the bad *** part)
12-05-2008, 12:45 AM
#40
Race Car
I'm just street driving, no track. I saw another thread where widening wheels was discussed. So I thought, what if I had my front tires widened in order to accomodate ridiculously wide tires (315+?) in the rear, and then put my current rear wheels in the front (I think they have 285's or 295's on them). Is that feasible? Goal would be to have wider tires for the supercharger plus I like the wide tire / bad *** car thing. (OK, 98% is the bad *** part)
Dan
'91 928GT S/C
475hp/460lb.ft
12-05-2008, 12:57 AM
#41
I would think the best thing for the street on the front would be a 275 max tire on a 9.5" wide wheel. You would want 69-70mm offset and you would only very slightly have to roll the fenders. 265's would fit in the front with those offset wheels without any modifications.
Dan
'91 928GT S/C 475hp/460lb.ft
Dan
'91 928GT S/C
475hp/460lb.ft
12-05-2008, 01:02 AM
#42
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Depends upon rim diameter------
315x25x19 / 19x11 wheel will work on your OB on the rear, however Porsche OEM wheels (19x10) will not work on the front---wrong offsets.
for street driving, you may find that 19x8 with 265/35/19 is plenty on the front.
18 inch diameter is a slightly different story>>>>>>>>>
--Russ
12-05-2008, 01:04 AM
#43
Depends upon rim diameter------
315x25x19 / 19x11 wheel will work on your OB on the rear, however Porsche OEM wheels (19x10) will not work on the front---wrong offsets.
for street driving, you may find that 19x8 with 265/35/19 is plenty on the front.
18 inch diameter is a slightly different story>>>>>>>>>
--Russ
315x25x19 / 19x11 wheel will work on your OB on the rear, however Porsche OEM wheels (19x10) will not work on the front---wrong offsets.
for street driving, you may find that 19x8 with 265/35/19 is plenty on the front.
18 inch diameter is a slightly different story>>>>>>>>>
--Russ
Also sorry if I've hijacked this thread a little, but I'm really curious about this...
thanks
12-05-2008, 01:09 AM
#44
Race Car
Dan
'91 928GT S/C
475hp/460lb.ft
12-05-2008, 01:10 AM
#45
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you can reference Wheel Dynamics website, or Andrew Olson's tire/wheel fitment guide found here on R-list.
between these two, you should find a fitment that you're looking for without body mods.
--Russ