erito Posted November 13, 2006 Share Posted November 13, 2006 The 'guide' recommend 2.0kg front and 2.5kg rear (if full load). I run my studded winter tires with 2.5 front and 2.5 rear. Is that a bad idea? From what i read, the car should be more stable if i lower the pressure front to 2.0.... Link to comment Share on other sites More sharing options...
wukindada Posted November 13, 2006 Share Posted November 13, 2006 Always higher in the front:) Toyota 6EATS .........SUCK!!!!!! Link to comment Share on other sites More sharing options...
erito Posted November 13, 2006 Author Share Posted November 13, 2006 Always higher in the front:) Really? Why? Link to comment Share on other sites More sharing options...
wukindada Posted November 13, 2006 Share Posted November 13, 2006 Due to front/back weight distribution....Think about it..... Where is the majority of the cars weight? Toyota 6EATS .........SUCK!!!!!! Link to comment Share on other sites More sharing options...
erito Posted November 13, 2006 Author Share Posted November 13, 2006 Due to front/back weight distribution....Think about it..... Where is the majority of the cars weight? That's what i always thought, but why do Subaru recommend 2.0kg front and 2.5 kg rear? In the text it say that overtaking will make rear more stable if the ratio front-rear in pressure is lower front. Link to comment Share on other sites More sharing options...
Guest Posted November 13, 2006 Share Posted November 13, 2006 What is the recommendation for USDM Outbacks? Link to comment Share on other sites More sharing options...
Garandman Posted November 13, 2006 Share Posted November 13, 2006 That's what i always thought, but why do Subaru recommend 2.0kg front and 2.5 kg rear? In the text it say that overtaking will make rear more stable if the ratio front-rear in pressure is lower front. Most manufacturer specs set the car up so it understeers. That gives the driver plenty of warning while they can still see out the front windshield.... You'll see in other threads here that most people run 1-2 psi less in the rear of a wagon to make it more neutral. From a calculator 1 psi = 0.0690 BAR = .0703 KG/CM but don't trust me.... Who Dares Wins スバル Link to comment Share on other sites More sharing options...
jersey2.5xt Posted November 13, 2006 Share Posted November 13, 2006 I am running 36 PSI in the front of my wagon and 34 PSI in the rear the car will turn in nicer and rear will tend to want to follow the nose better, vary the pressures more and the car will tend to oversteer as the rear tires roll onto the side wall thus breaking traction @ the rear of the car first. VVG hit the nail on the head. most people when faced with sliding situation (under or oversteer) tend to apply brakes first then maybe steer, this situation will exxagerate an oversteer situation and will just plain solve a understeer situation. All any car needs to do to recover from understeer is slow down. to recover from oversteer is counter intuitive for most of the world steer then apply throttle this is especially true in the USA where all you need to get a licsense is a heartbeat and a pulse! So almoast everything that is sold stateside is designed to understeer so that the morons can drive with out killing themselves. Point in this case. Remember the original Audi TT, it had no wing on it. then after multiple high speed crashes in europe. Audi came out with an update that included rear springs, control arms and a wing the rear springs were softer and the control arms redesigned and the wing incorporated to "deaden" the car. Initially they were designed as a neutral/slight oversteer car, which made them "tack sharp" in there response to driver input but they were tough for a beginner to drive fast as exhibited by the crash's So they became less fun and more safe... Link to comment Share on other sites More sharing options...
amex Posted November 13, 2006 Share Posted November 13, 2006 Erito, I am also running studded winter tires and I run 2.0 kg front and 1.90 kg back that sets the car up for three people and luggage. If you check your recommendation guide again you will see that you are reading it wrong. I did that same thing as well before. You should run 2.5 kg front and 2.5 kg back for 5 people and luggage as recommended by your guide. Link to comment Share on other sites More sharing options...
erito Posted November 14, 2006 Author Share Posted November 14, 2006 Erito, I am also running studded winter tires and I run 2.0 kg front and 1.90 kg back that sets the car up for three people and luggage. If you check your recommendation guide again you will see that you are reading it wrong. I did that same thing as well before. You should run 2.5 kg front and 2.5 kg back for 5 people and luggage as recommended by your guide. Okay thanx Amex. You seem to run with very low numbers. What kind of tires do you have? Maby i should lower my because it is not very often i have five people + stuff in my car.... Link to comment Share on other sites More sharing options...
amex Posted November 14, 2006 Share Posted November 14, 2006 Okay thanx Amex. You seem to run with very low numbers. What kind of tires do you have? Maby i should lower my because it is not very often i have five people + stuff in my car.... I am running on Nokian hakkapeliitta 4 with studs as I live on the country side, so I am looking for the best grip out here, when we get lots of snow and ice it is the real deal as you should know. Last winter my car work like a charm and I am loving it. Link to comment Share on other sites More sharing options...
erito Posted November 14, 2006 Author Share Posted November 14, 2006 I am running on Nokian hakkapeliitta 4 with studs as I live on the country side, so I am looking for the best grip out here, when we get lots of snow and ice it is the real deal as you should know. Last winter my car work like a charm and I am loving it. Yes my Hakka 4 are awsome. And the car also, but i will test run with lower kg just to see how the car feels. Last weekend we had alot of ice and slush and i met some maniac driving "chicken race" in the night. I had to drive off the road, down the side and almost flipped over. Real bad but soft 'crash' and i thought i had to call someone to tow me up and then the insurance company, car repair etc. But all i had to do was to put i reverese, give alot of gas, enjoy a bumpy nervous ride up to the road and then wash the car.... incredible. Link to comment Share on other sites More sharing options...
arumis555 Posted November 14, 2006 Share Posted November 14, 2006 The 'guide' recommend 2.0kg front and 2.5kg rear (if full load). I run my studded winter tires with 2.5 front and 2.5 rear. Is that a bad idea? From what i read, the car should be more stable if i lower the pressure front to 2.0.... Front 220 (2.2, 32) , Rear 210 (2.1, 30) kPa (kgf/cm2, psi) for all tires of R16 and R17 exept 215/45ZR17. If fully loaded or towing a trailer, pressure for rear tire can be increased to 220 kPa. During the hard winter conditions , when increased grip is needed, tire pressure can be decreased down to 210 ( front) and 200 (rear). But low pressure will increase tire wear and fuel consumption. It is very important that for correct AWD behaviour rotation speed for front and rear axles MUST be the same - that is why corect inflation of Subaru tires is essential. Othervice it will result in severe mechanical damage to the drive train. For example , lets say we have MT , during straight-line driving on a flat road at a constant speed, all the four wheels rotate at the same speed. Then the center differential delivers engine torque evenly to the front and rear wheels. The viscous coupling does not generate shear torque because there is no relative movements between the inner and outer plates. If tire pressure is incorrect , the resulting speed difference between the front and rear drive shafts causes the viscous coupling to generate significant amount of shear torque. As a result, the torque distributed to the more inflated wheels becomes larger than that distributed to the less inflated wheels ( axles ). If these conditions persist for long time and during high speed, viscous coupling will overheat. Link to comment Share on other sites More sharing options...
MDW25gt Posted November 14, 2006 Share Posted November 14, 2006 Due to front/back weight distribution....Think about it..... Where is the majority of the cars weight? 38psi front 36psi rear, because of what he said. engine in front. If I am loaded I bump the rear up 2psi Link to comment Share on other sites More sharing options...
MDW25gt Posted November 14, 2006 Share Posted November 14, 2006 Most manufacturer specs set the car up so it understeers. That gives the driver plenty of warning while they can still see out the front windshield.... You'll see in other threads here that most people run 1-2 psi less in the rear of a wagon to make it more neutral. From a calculator 1 psi = 0.0690 BAR = .0703 KG/CM but don't trust me.... kg is not the correct units to use in this case. It should be kg/cm2! Bar is the more appropriate unit to use. Its like saying you cars weight is 1.5ton. a more precise unit to use is 3000lbs.or 1360.079kg. Link to comment Share on other sites More sharing options...
amex Posted November 14, 2006 Share Posted November 14, 2006 Front 220 (2.2, 32) , Rear 210 (2.1, 30) kPa (kgf/cm2, psi) for all tires of R16 and R17 exept 215/45ZR17. If fully loaded or towing a trailer, pressure for rear tire can be increased to 220 kPa. During the hard winter conditions , when increased grip is needed, tire pressure can be decreased down to 210 ( front) and 200 (rear). But low pressure will increase tire wear and fuel consumption. It is very important that for correct AWD behaviour rotation speed for front and rear axles MUST be the same - that is why corect inflation of Subaru tires is essential. Othervice it will result in severe mechanical damage to the drive train. For example , lets say we have MT , during straight-line driving on a flat road at a constant speed, all the four wheels rotate at the same speed. Then the center differential delivers engine torque evenly to the front and rear wheels. The viscous coupling does not generate shear torque because there is no relative movements between the inner and outer plates. If tire pressure is incorrect , the resulting speed difference between the front and rear drive shafts causes the viscous coupling to generate significant amount of shear torque. As a result, the torque distributed to the more inflated wheels becomes larger than that distributed to the less inflated wheels ( axles ). If these conditions persist for long time and during high speed, viscous coupling will overheat. (1) Arumis, what are you trying to say? Are you saying that Subaru’s tires recommendations are wrong? Can you please tell us where you got your tires recommendation from? Do you set yours up as 220 front and 210 rear? Were did you find those numbers? (2) We are talking about winter tires and no car goes in a straight line all the time in the winter. If I am wrong can you please tell me? Let’s say that you are driving on a highway that is full of snow and ice, which means that you car is constantly looking for the best grip and delivering torque/grip to the wheel/wheels which has the best grip and your tire pressure must be correct at all times, am I wrong in thinking this?????? Or do you know something that we do not? Link to comment Share on other sites More sharing options...
erito Posted November 15, 2006 Author Share Posted November 15, 2006 I now run with 2.2 front and 2.1 rear. Much smoother and better ride than 2.5/2.5 as i had before. Link to comment Share on other sites More sharing options...
arumis555 Posted December 4, 2006 Share Posted December 4, 2006 (1) Arumis, what are you trying to say? Are you saying that Subaru’s tires recommendations are wrong? Can you please tell us where you got your tires recommendation from? Do you set yours up as 220 front and 210 rear? Were did you find those numbers? (2) We are talking about winter tires and no car goes in a straight line all the time in the winter. If I am wrong can you please tell me? Let’s say that you are driving on a highway that is full of snow and ice, which means that you car is constantly looking for the best grip and delivering torque/grip to the wheel/wheels which has the best grip and your tire pressure must be correct at all times, am I wrong in thinking this?????? Or do you know something that we do not? OK, I'll try to explain... Regarding 1's issue , I'm not sure that You are using correct "guide". I'v checked several sources and info frm them are in pictures below: Label 1 on 2005 Outback. http://i90.photobucket.com/albums/k251/upelis/label1.jpg Label 1 on 2005 Outback. http://i90.photobucket.com/albums/k251/upelis/label2.jpg Subaru Outback owner's manual 2005 http://i90.photobucket.com/albums/k251/upelis/usermanual.jpg table means that if You are checking tyre pressure in warm garage, You have to inflate them up to 270/260 kPa in order to have 220/210 kPa at minus 23C. But keep in mind that during driving tyre temperature increases , pressure increases too 2005 repair manual: http://i90.photobucket.com/albums/k251/upelis/repairmanual.jpg So , I was unable to find any references that says 250kPa is the correct tyre pressure. Regarding 2'nd issue: You are completely right when saying that "tire pressure must be correct at all times". Unfortunatelly driving conditions may vary during this time. And theoretically tyre pressure can be adjusted in order to fullfill changing conditions , but you can gain one think and loose another. That depends on what actually You need at that moment. For example, if You are participating in the competition for best MPG , then You can increase tyre pressure twice, but that is not correct tyre pressure for "daily" driving. The same with soft surfaces (mud, sand, snow) .These particularly troublesome as the wheels can rapidly dig themselves pits out of which they cannot climb. You can reduce tyre pressure on 10-20 kPa - this gives a bigger ground footprint, hence lower pressure on the soft surface. But drive slowly with deflated tyres, and don't turn too sharply or they may fall off the rim, and don't drive on hard surfaces. So , this recommendation is only for "special ocasions" . Reinflate tyres when on hard surface. Link to comment Share on other sites More sharing options...
Viss1 Posted July 19, 2007 Share Posted July 19, 2007 Being new to AWD, I'm wondering if Subaru recommends lower rear tire pressure in order to maintain equal tire diameter front to back and preserve the center diff/viscous coupling. Anyone have any thoughts? Link to comment Share on other sites More sharing options...
Mach V Dan Posted July 19, 2007 Share Posted July 19, 2007 38psi front 36psi rear, because of what he said. engine in front. If I am loaded I bump the rear up 2psi That's your cold tire pressure? Those pressures are very high. You will get good mileage, but you will see reduced grip and increased wear in the center of your tread because the tires will bulge up in the center. --Dan Mach V FastWRX.com Link to comment Share on other sites More sharing options...
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