emlevins Posted June 10, 2005 Share Posted June 10, 2005 Guys - Just put Goodyear Eagle F1 GS-D3s on the stock wheels to replace the RE-92s. I've been fiddling with tire pressure. Started with 38-34 and then went to 42-40. I'll reserve comment at this point but........ Anyone have suggestions? I've never had summer only tires in my life and would be interested in folks offering a tire pressure range within which I can fiddle safely. Thanks all. 05 SWP Legacy GT Limited (aka "Pearl")- 5MT AP - Stage 2 Protuned (238/284) - wife driven 07 BMW 335xi Link to comment Share on other sites More sharing options...
Drift Monkey Posted June 10, 2005 Share Posted June 10, 2005 Each tire is different, though I know the Eagle F1's have somewhat of a mushy sidewall...so a higher pressure would work well. 42-40 sounds about right but you can adjust up or down according to needs of comfort or sidewall stiffness... Link to comment Share on other sites More sharing options...
emlevins Posted June 10, 2005 Author Share Posted June 10, 2005 DM - How far up do you think I could adjust SAFELY? Thats my primary concern because even at 42-40 it is an unbelievably soft ride (you can barely feel railroad tracks) and steering responsiveness improved dramatically (you barely turn the wheel and the car responds) when I upped psi from 38-34. 05 SWP Legacy GT Limited (aka "Pearl")- 5MT AP - Stage 2 Protuned (238/284) - wife driven 07 BMW 335xi Link to comment Share on other sites More sharing options...
Drift Monkey Posted June 10, 2005 Share Posted June 10, 2005 DM - How far up do you think I could adjust SAFELY? Thats my primary concern because even at 42-40 it is an unbelievably soft ride (you can barely feel railroad tracks) and steering responsiveness improved dramatically (you barely turn the wheel and the car responds) when I upped psi from 38-34. What is the max psi on the tire on the sidewall? Link to comment Share on other sites More sharing options...
emlevins Posted June 10, 2005 Author Share Posted June 10, 2005 What is the max psi on the tire on the sidewall? 50 - so I guess anything "comfortably" short of that is OK, huh? 05 SWP Legacy GT Limited (aka "Pearl")- 5MT AP - Stage 2 Protuned (238/284) - wife driven 07 BMW 335xi Link to comment Share on other sites More sharing options...
deneb Posted June 11, 2005 Share Posted June 11, 2005 Those tires seem pretty impressive! Any difference in road noise? Link to comment Share on other sites More sharing options...
meier motor sports Posted June 11, 2005 Share Posted June 11, 2005 iv got em to. i like em so far Link to comment Share on other sites More sharing options...
puzzled Posted June 11, 2005 Share Posted June 11, 2005 i also have them. been running at 40/36 Link to comment Share on other sites More sharing options...
stewthebassman Posted June 11, 2005 Share Posted June 11, 2005 http://legacygt.com/forums/showthread.php?t=6284 Here is a great thread on this topic. I just pumped my RE-92s up to 39-37 and already the difference is night and day. This should be the stock pressure! And as the man says, max pressure as per the sidewall is acceptable too...did you ever play with TP on your RE-92s? Link to comment Share on other sites More sharing options...
SUBE555 Posted June 11, 2005 Share Posted June 11, 2005 I haven't found a reason to change my tire pressure habbits with the seasons, just accomodate for changes in atmospheric temps. Link to comment Share on other sites More sharing options...
emlevins Posted June 11, 2005 Author Share Posted June 11, 2005 Those tires seem pretty impressive! Any difference in road noise? Road noise generally seems no different than the RE-92s....very quiet...but I have very little wear on them at this point in time. 05 SWP Legacy GT Limited (aka "Pearl")- 5MT AP - Stage 2 Protuned (238/284) - wife driven 07 BMW 335xi Link to comment Share on other sites More sharing options...
Drift Monkey Posted June 11, 2005 Share Posted June 11, 2005 50 - so I guess anything "comfortably" short of that is OK, huh?You're fine, just adjust the fronts to anything nominaly under that and you'll be safe. Link to comment Share on other sites More sharing options...
Xantium Posted June 14, 2005 Share Posted June 14, 2005 Any reason that the fronts have to be higher than the rears... i'd like to put the rears higher... i dont like understeer. Link to comment Share on other sites More sharing options...
Drift Monkey Posted June 14, 2005 Share Posted June 14, 2005 Any reason that the fronts have to be higher than the rears... i'd like to put the rears higher... i dont like understeer. You can for specific applications such as autox, but from what I understand, the center diff doesn't like it when the rears are at a higher pressure... You car is front weight loaded (the engine bay is a tad bit heavier than the trunk area of the car), the front tires see more weight than the rear ones do. If they were equal pressures, your front tires would be slightly more compressed, have a smaller effective diameter, and would rotate *more* than the rear tires do just travelling along. To balance that out, you need to have some pressure bias towards the front. Equal pressures -> front wheels spin more than rear wheels -> center differential works hard, all the time, just driving along Pressure biased towards the front in correct ratio -> center diff does little to no work just driving along Link to comment Share on other sites More sharing options...
praedet Posted June 14, 2005 Share Posted June 14, 2005 And to add on to DM, the car will "feel" like it is oversteering with less air in the rear. This is due to rolling on to the sidewall while turning. Until you get to 8-10/10ths, less air in the rear/more in the front feels like oversteer. If you have them equal and are driving at road safe speeds, it will feel like the car is understeering due to the front tires rolling onto the sidewalls first... Ted Link to comment Share on other sites More sharing options...
Drift Monkey Posted June 14, 2005 Share Posted June 14, 2005 And to add on to DM, the car will "feel" like it is oversteering with less air in the rear. This is due to rolling on to the sidewall while turning. Until you get to 8-10/10ths, less air in the rear/more in the front feels like oversteer. If you have them equal and are driving at road safe speeds, it will feel like the car is understeering due to the front tires rolling onto the sidewalls first... Ted MORE pressure in the rear will decrease the tire's contact patch creating oversteer. Only severly underinflated rear tires will cause the same effect. Link to comment Share on other sites More sharing options...
melayout Posted June 14, 2005 Share Posted June 14, 2005 So 41/39 should give me more oversteer than 35/33 ? Oversteer is always welcomed over understeer. I tried it in the rain, the car oversteered, I countersteered, it oversteers to the other side, I countersteer, all while going WOT and the car just magically straightens up and shoots forward. I keed I keeed Link to comment Share on other sites More sharing options...
Drift Monkey Posted June 14, 2005 Share Posted June 14, 2005 So 41/39 should give me more oversteer than 35/33 ? Oversteer is always welcomed over understeer. I tried it in the rain, the car oversteered, I countersteered, it oversteers to the other side, I countersteer, all while going WOT and the car just magically straightens up and shoots forward. Neither will promote oversteer under stock conditions because the pressures are still proplerly biased towards the front... Link to comment Share on other sites More sharing options...
praedet Posted June 14, 2005 Share Posted June 14, 2005 DM, I am not talking about what the car is doing, I am talking about what it feels like. To get the car to truly under/oversteer you have to be pushing pretty hard. In normal driving, the feel of the tires rolling onto the sidewalls will actually "feel" like under/oversteer depending on which set does it first. So, for autocross/track, more rear pressure will indeed bring out the tail more. But, for day to day driving, knocking down the rear will actually "feel" like oversteer. Try it, you will be amazed. I didn't believe it until I thought about it for a while and then tried it... Ted Link to comment Share on other sites More sharing options...
melayout Posted June 14, 2005 Share Posted June 14, 2005 This means you are going beyong the 2 PSI difference between the rear and front, which just makes the center diff work harder and is not something you can run all the time, so basically useless. I keed I keeed Link to comment Share on other sites More sharing options...
Drift Monkey Posted June 14, 2005 Share Posted June 14, 2005 This means you are going beyong the 2 PSI difference between the rear and front, which just makes the center diff work harder and is not something you can run all the time, so basically useless. Not for events. Link to comment Share on other sites More sharing options...
Drift Monkey Posted June 14, 2005 Share Posted June 14, 2005 DM, I am not talking about what the car is doing, I am talking about what it feels like. To get the car to truly under/oversteer you have to be pushing pretty hard. In normal driving, the feel of the tires rolling onto the sidewalls will actually "feel" like under/oversteer depending on which set does it first. So, for autocross/track, more rear pressure will indeed bring out the tail more. But, for day to day driving, knocking down the rear will actually "feel" like oversteer. Try it, you will be amazed. I didn't believe it until I thought about it for a while and then tried it... Ted I wouldn't know. I have 225/45/18 Azenis. What sidewall roll? Link to comment Share on other sites More sharing options...
Xenonk Posted June 14, 2005 Share Posted June 14, 2005 you can always tire chalk the sidewall to see if you are rolling over the tire (too low of a tire pressure).. you dont want to over inflate or you'll just end up ballooning the tire and lessen the contact patch. The thing to look for is putting enough tire pressure to hold the car up correct (load weight) and finding a happy medium with steering response and maximizing contact patch to either extend the tire's tread life or maximize grip performance. Keefe Keefe Link to comment Share on other sites More sharing options...
Drift Monkey Posted June 15, 2005 Share Posted June 15, 2005 Right, I think the key is inflating to get maximum contact patch without sacrificing sidewall strength. Balooning can be used for the strip though... Link to comment Share on other sites More sharing options...
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