Guest turboman Posted December 18, 2004 Share Posted December 18, 2004 After endless hours of research by my dedicated staff the tire that comes out ahead is a Pirelli P Zero Nero M+S in size 205/40-17 for stock GT wheels @ $99 each from Tire rack. It had the highest rankings in almost every category, plus being acceptable in snow. The RE-92's will scrapped and used as wheel chocks in my hanger for the Lear. :lol: The Pirellis are 1" smaller diameter that the stock tires, lowering the car by 1/2". The gearing reduction will equal going from a 4.11 rear to a 4.33. A gearing change gives a direct increase in acceleration, and unfortunately a 5% higher speedo reading than actual speed. (60mph indicated = 57mph actual) Of course the speedo has to be checked for trueness against the one mile signs on the Interstate. Read somewhere that a given percentage increase in horsepower gives the "square" of the percentage in ACTUAL acceleration, meaning 25% increase in HP equals 5% in acceleration. If true, this means a 5% gearing reduction would equal an increase of 45hp enginewise. (Basing a mythical 185 actual dyno hp @ the wheels). ...just one opinion. Don't pick up the new car until Monday. Link to comment Share on other sites More sharing options...
Random Posted December 18, 2004 Share Posted December 18, 2004 You might want to redo your math... I don't think you'll see anything CLOSE to an extra 5% acceleration or an extra 45 WHP. using your math, you might want to consider you'll be racking up an extra 5% in the mileage department, and working your engine harder to go the same speed as stock tire size. Link to comment Share on other sites More sharing options...
Guest turboman Posted December 18, 2004 Share Posted December 18, 2004 [quote name='Random']You might want to redo your math... I don't think you'll see anything CLOSE to an extra 5% acceleration or an extra 45 WHP. using your math, you might want to consider you'll be racking up an extra 5% in the mileage department, and working your engine harder to go the same speed as stock tire size.[/QUOTE] Yes, there will be a slight loss in fuel economy, just like when you increase HP. After 25 years of running Solo II and I with approx. 30 different cars. Two Midwest class championships, (Pantera '74, Rabbit '78), about 120 trophies, and having my book "How to win at Slalom and Autocross" published by Sportscar press and Road & Track in 1974, and changing axle ratios and tire sizes 100's of times my data is accurate. Check under Google or Amazon. "Jim Pagel, autocross". It's out of print but there are some used copies available. Sorry, not bragging. Just trying to establish a modicum of credibility in a new forum. NASOIC, AR-15.com, ATV-Frontier, and 1911forum are my usual hangouts. Another cliche you might like (hate) every pound reduction in unsprung weight is the same as reducing 10 pounds gross weight in improved handling and acceleration. Wheels, tires, flywheels, pulleys, suspensions. Chew on that one for a while. :mad: Link to comment Share on other sites More sharing options...
rkkwan Posted December 18, 2004 Share Posted December 18, 2004 The 205/40R17 has a load rating of 84, which is 1,102lb. Our car, when when empty, will have about 1,000lb for the front, and will exceed the load rating when loaded. A conservative and reputable retailer, like Luke @ Tirerack, definitely will not sell you this tire for a LGT. Yes, a taller gearing may help your acceleration a little, so does unsprung weight. But 45HP? Give me a break. If that's true, we should all use smaller brakes and put tiny 13" tires on the car. And there are circumstances when you may be at a disadvantage, like if you hit redline in 2nd gear in an auto-x. But, why would someone run an all-season tire for auto-x to start with? Or are you not running these tires for auto-x? I'm confused. Link to comment Share on other sites More sharing options...
fan42025 Posted December 18, 2004 Share Posted December 18, 2004 Does this mean going the other way and using 225's will reduce my power by around 45hp? I DON"T THINK SO. Also, I'd never buy Pirelli due to their softer walls and pot hole unfriendliness. Link to comment Share on other sites More sharing options...
hodgeee Posted December 18, 2004 Share Posted December 18, 2004 Doing you math backwards, means the 225, .5" taller tires and the 6lb increase in weight would gather a 240lb negative advantage for the 10% increase in performance loss for every pound gained, and the ratio for the increase in tire size would go from 4.11 to 3.93, with a 12.5% loss in power which calculates to 22hp less, which in turn for the averaged #'s in drag racing would lead to a .44 second reduction in quarter mile times, on average mind you! Hmmmmm, I couldn't detect any loss of power, maybe the average drop of temperature came down about 10 degrees right before I put my tires on which eguates to about 10 hp at the wheels due to denser air, then the weight I lost before the holiday season was about 20 lbs which would make up for the unsprung weight increase of 24lbs from the tirews, thus giving back another 8 hp, so maybe I only lost 4 to 6 hp overall, and that is why I couldn't detect the power loss. OHHHHHHHHH, I know the car has a clearance of 5", so if your 205 drops it 1", which equates to .5" of clearance then I am going to go with 195/20/16's which reduce overall diameter by 6 inches wich eguates to 4.11 to 5.43 gearing leaving me 2" of ground clearance so I can go over any rocks that might get on the street, this 30% reduction would then lead to a hp gain of 95hp, of course using a mythical 185 at the tires hp rating. Man forget the accessport and any other stuff, what a waste of money, I am going to Discount tire right now!! 350 at the engine here I come. Cool I just wanted to be in the 350hp range to make me happy, and now I have it. Link to comment Share on other sites More sharing options...
SBT Posted December 18, 2004 Share Posted December 18, 2004 [quote name='hodgeee']Doing you math backwards, means the 225, .5" taller tires and the 6lb increase in weight would gather a 240lb negative advantage for the 10% increase in performance loss for every pound gained, and the ratio for the increase in tire size would go from 4.11 to 3.93, with a 12.5% loss in power which calculates to 22hp less, which in turn for the averaged #'s in drag racing would lead to a .44 second reduction in quarter mile times, on average mind you! Hmmmmm, I couldn't detect any loss of power, maybe the average drop of temperature came down about 10 degrees right before I put my tires on which eguates to about 10 hp at the wheels due to denser air, then the weight I lost before the holiday season was about 20 lbs which would make up for the unsprung weight increase of 24lbs from the tirews, thus giving back another 8 hp, so maybe I only lost 4 to 6 hp overall, and that is why I couldn't detect the power loss. OHHHHHHHHH, I know the car has a clearance of 5", so if your 205 drops it 1", which equates to .5" of clearance then I am going to go with 195/20/16's which reduce overall diameter by 6 inches wich eguates to 4.11 to 5.43 gearing leaving me 2" of ground clearance so I can go over any rocks that might get on the street, this 30% reduction would then lead to a hp gain of 95hp, of course using a mythical 185 at the tires hp rating. Man forget the accessport and any other stuff, what a waste of money, I am going to Discount tire right now!! 350 at the engine here I come. Cool I just wanted to be in the 350hp range to make me happy, and now I have it.[/QUOTE]Holy crap Batman, that's a ton to absorb ---- and worse yet, it all made sense, kinda... but I'm still thinking an calculatin' ;) SBT - Pro amore Dei et patriam et populum - Link to comment Share on other sites More sharing options...
mmanus88 Posted December 18, 2004 Share Posted December 18, 2004 you shouldve checked out the toyo proxes 4's. cheaper and i saw higher ratings on some websites regarding most (if not every) aspect fo driving Link to comment Share on other sites More sharing options...
rporter Posted December 19, 2004 Share Posted December 19, 2004 FWIW, the stock tires give a 2% high reading on the speedo & odo, so shorter tires will increase that. Heavier/lighter tires give anywhere from a 1 to 11x dynamic loading factor depending on where the weight is added/subtracted. The most common, conservative number to use is 4x the static weight change, up to 7x as a top-end conservative calculation. The only real difference has nothing to do with HP (remember that HP is a purely mathematical calculation of torque over time), but the overall weight and gearing willl matter. From personal experience, a slightly shorter diameter doesn't matter as much as reducing the weight of the wheel/tire combo. For alll of the whining and bitching, I have found the RE92s to be "OK" in bad weather so far. I had considered the Nero M&S for the winter, and I may get them when the 92s wear out. I have Pilot Exaltos for the summer, and I believe in two sets of wheels/tires up here in the cold weather. Ron Link to comment Share on other sites More sharing options...
frontrangeSubie Posted December 19, 2004 Share Posted December 19, 2004 Great choice in tires....I got those on my car...except I got the OEM size.... Dont know why you would want to lower the tire as it is a low profile as it is....any pebble in the road and you will feel it.... Link to comment Share on other sites More sharing options...
godwhomismike Posted December 19, 2004 Share Posted December 19, 2004 I am probably going to get these tires in the Spring. I detest the stock tires and the dealership will be getting the car back at the end of my lease wearing them - I got them and they can have them back. I have heard nothing but great things with the Pirelli P-Zero Nero M+S, and it looks like that's what I'll get. I'd love to see a head to head with the Pirelli vs the Toyo's in how it handles in rain, snow, and dry. - Mike Link to comment Share on other sites More sharing options...
Guest turboman Posted December 19, 2004 Share Posted December 19, 2004 [quote name='rkkwan']The 205/40R17 has a load rating of 84, which is 1,102lb. Our car, when when empty, will have about 1,000lb for the front, and will exceed the load rating when loaded. A conservative and reputative retailer, like Luke @ Tirerack, definitely will not sell you this tire for a LGT. Yes, a taller gearing may help your acceleration a little, so does unsprung weight. But 45HP? Give me a break. If that's true, we should all use smaller brakes and put tiny 13" tires on the car. And there are circumstances when you may be at a disadvantage, like if you hit redline in 2nd gear in an auto-x. But, why would someone run an all-season tire for auto-x to start with? Or are you not running these tires for auto-x? I'm confused.[/QUOTE] A 3500 lb car with 54% of the weight on the front is 1890lbs/2= 945lbs per wheel. Subaru engines are as far back and as far down as they can get them. And the engine is aluminum. Basing on assumption that driver's mass is in the middle. Besides I'll just tell luke that they're for my PT Cruiser. Yes, there were times in an autocross when a short rear axle ratio, or lower tire, will require one more shift. In a '63 Corvette I changed from a 3.70 to a 4.56 and 1st was virtually worthless. Nothing but wheel spin. All the cars I've run have always had the lowest profile I could get. Both for stiffer sidewall and lower ride height. In the '60's and '70's there weren't many low profiles until the "wide oval" 60 series Firestones came out in '68 I believe. On a '76 Rabbit I ran unbeatable Phoenix tires that were 18" OD if I recall correctly.(they were the legal "cheaters' of the year) The 45hp figure is related to acceleration percentage gain being the "square" of the percentage of hp increase. It's too complicated to explain here. Just forget you saw it.... No, I'm not autocrossing anymore but I've just got the habit of maximizing my cars. Bad habit. On the WRX I ran Azenis Sports for autocrosses when they first came out in '02 and they were THE tire, and they were great. But since my heart attack and complications in '92 I found my my autocross days are over. Too hard to walk the course before the event. :( Link to comment Share on other sites More sharing options...
frontrangeSubie Posted December 19, 2004 Share Posted December 19, 2004 [quote name='godwhomismike']I am probably going to get these tires in the Spring. I detest the stock tires and the dealership will be getting the car back at the end of my lease wearing them - I got them and they can have them back. I have heard nothing but great things with the Pirelli P-Zero Nero M+S, and it looks like that's what I'll get. I'd love to see a head to head with the Pirelli vs the Toyo's in how it handles in rain, snow, and dry. - Mike[/QUOTE] Mike, these Pirelli's are performing really well in the snow up here in the Rockies (thats why I got them).....and for an all season tire, that's good....Im not changing to snow tires every Winter... Link to comment Share on other sites More sharing options...
hodgeee Posted December 19, 2004 Share Posted December 19, 2004 Just bustin your balls turboman about my calculations, welcome to the site, enjoy the car, but I woulnd't run any lower tire ratio or gearing than the stock. It already feels like first gear is way to short now. You would be better running some strong lightweight racing wheels to just drop off weight for better power and handling. I just couldn't find any that appealed to my taste for looks. I did a gear swap on my lowered truck to a taller 4.11 from a 3.73 and went from a 28" tall tire to a 26" tall tire. It made wheel spin crazy but still from running at the track, I only got a .1 second reduction in et. with slicks, which equated to about 10hp, that was also loosing 8lbs per tire. I don't beleive that the calculation takes everything into factor. 45hp does not seem feasible at all for what you are looking at doing. Link to comment Share on other sites More sharing options...
rkkwan Posted December 19, 2004 Share Posted December 19, 2004 Well, let just say that most of us here don't see your point. You buy a tire that is narrower (i.e. less cornering grip), is shorter (i.e. possibly worse ride), has lower load rating (may be dangerous), increases the odometer reading by 5% (decreasing resale value of car), decreases ground clearance, and in my opinion ridiculously looking on a GT wagon (but please post pictures if possible) - to do what? Get a tiny bit better acceleration. And you don't auto-x anymore, so are you going to the 1/4 track? But hey, to each his own. I'm just warning you about potential problem with the low-load rating tires. Don't come back to tell us about tire mishaps... Link to comment Share on other sites More sharing options...
Guest turboman Posted December 19, 2004 Share Posted December 19, 2004 [quote name='rkkwan']The 205/40R17 has a load rating of 84, which is 1,102lb. Our car, when when empty, will have about 1,000lb for the front, and will exceed the load rating when loaded. A conservative and reputable retailer, like Luke @ Tirerack, definitely will not sell you this tire for a LGT. [/QUOTE] Makes me wonder where everyone is getting their Pirelli P Zero Nero M&S's. Every 16" or 17" size has a load rating of 1074 lbs. :lol: By the way, the 215/45-17 Nero is coded "SL" by TireRack. Their coding for Subaru Legacy (1074 lbs). :lol: :lol: :lol: Link to comment Share on other sites More sharing options...
agctr Posted December 19, 2004 Share Posted December 19, 2004 Yup have to agree the NERO's are the way to go and you have the coin to shell out for them. Adam. Link to comment Share on other sites More sharing options...
fan42025 Posted December 19, 2004 Share Posted December 19, 2004 Not in pot hole city Sydney. [quote name='agctr']Yup have to agree the NERO's are the way to go and you have the coin to shell out for them. Adam.[/QUOTE] Link to comment Share on other sites More sharing options...
sduford Posted December 19, 2004 Share Posted December 19, 2004 [quote name='turboman']Makes me wonder where everyone is getting their Pirelli P Zero Nero M&S's. Every 16" or 17" size has a load rating of 1074 lbs. :lol: [/QUOTE] That is incorrect, the load ratings vary from 83W to 98W. The 225/45-17 has a load rating of 1324 lbs. The 235/55-17 which I am looking at for my OBXT has a load rating of 1653 lbs. Sly Sylvain www.digitalfotographer.com - Audi Q5 Club - MB-GLK Club Link to comment Share on other sites More sharing options...
Guest turboman Posted December 19, 2004 Share Posted December 19, 2004 Don't know why I wanted to go lower profile (40's) when I've experienced the negative effects. You feel every bump in the road and wheel damage is too easy. This is the first time I've chosen a car NOT for Solo 2 and it's a strange experience. Being the fastest on expressway ramps and pulling the car next to me at a stoplight when the roads are slippery are still my greatest driving pleasure. I should have gotten into "wheel-to-wheel" years ago but fate didn't go that way. Hope I haven't waste space on this forum. Picked up the new car a few hours ago and it's really nice. Got the burning clutch smell. Salesman said it takes about 700 miles for it to go away. Doesn't seem right though. Subaru knows how to make a clutch that doesn't stink. ...enough rambling on. Everyone have a Merry Christmas and drive carefully. :) Link to comment Share on other sites More sharing options...
Guest turboman Posted December 19, 2004 Share Posted December 19, 2004 [quote name='sduford']That is incorrect, the load ratings vary from 83W to 98W. The 225/45-17 has a load rating of 1324 lbs. The 235/55-17 which I am looking at for my OBXT has a load rating of 1653 lbs. Sly[/QUOTE] Your OBXT doesn't have [U]Pirellis[/U]. TireRack doesn't have those sizes listed for a Pirelli P Nero 17". If you'll check the "spec" listing it gives the load capacities of the sizes available which is what I stated. Link to comment Share on other sites More sharing options...
sduford Posted December 19, 2004 Share Posted December 19, 2004 [quote name='turboman']Your OBXT doesn't have [u]Pirellis[/u]. TireRack doesn't have those sizes listed for a Pirelli P Nero 17". If you'll check the "spec" listing it gives the load capacities of the sizes available which is what I stated.[/QUOTE] Well, you obviously didn't read my email: they do have the 235/55-17, which is the one I'm looking at as I stated above. Yes it is in theory larger then the factory specified 225/55-17s, but if you look at the dimensions, you'll see that it is actually small for a 235/55 and it is almost EXACTLY the same size as the Michelin Pilot Sport A/S in 225/55-17. That tire will fit just fine and will not cause any noticeable speedometer error. We're talking about the P-Zero Nero M&S here, perhaps you are looking at the non all-season P-Zero Nero (no M&S)? Sly Sylvain www.digitalfotographer.com - Audi Q5 Club - MB-GLK Club Link to comment Share on other sites More sharing options...
rkkwan Posted December 19, 2004 Share Posted December 19, 2004 [url]http://www.tirerack.com/tires/Spec.jsp?make=Pirelli&model=PZero+Nero+M%26S[/url] Read it yourself, turboman. Here are the common sizes for all current non-OB Subarus: [B]PZero Nero M+S[/B] 205/55r16 91W 1356lb 225/50r16 92W 1385lb 215/45r17 87W 1202lb 225/45r17 90W 1324lb 225/40r18 88W 1235lb Link to comment Share on other sites More sharing options...
Guest turboman Posted December 19, 2004 Share Posted December 19, 2004 [quote name='rkkwan'][url]http://www.tirerack.com/tires/Spec.jsp?make=Pirelli&model=PZero+Nero+M%26S[/url] Read it yourself, turboman. Here are the common sizes for all current non-OB Subarus: [B]PZero Nero M+S[/B] 205/55r16 91W 1356lb 225/50r16 92W 1385lb 215/45r17 87W 1202lb 225/45r17 90W 1324lb 225/40r18 88W 1235lb[/QUOTE] Thanks for the true info. I was apparently looking under NON M&S tires. There's plenty of big enough sizes to choose from. I'm calling Monday to order before it's too late in the season, then I'll run these all year. Appreciqate the time it took you to set a dummy straight. Good man... :p Link to comment Share on other sites More sharing options...
rporter Posted December 19, 2004 Share Posted December 19, 2004 One other nice thing about Pirellis is that they try to make lightweight tires (per an article in a car mag a few years back). I had some P7000 SuperSports a few years ago, which I liked a lot, and in the 225/50/16 size, they were only 22 pounds. I wish Tire Rack listed tire weights (although I understand that if you ask them, they do have weights for many of their tires), I'll bet the P Zero Nero is relatively light for it's size. Ron Link to comment Share on other sites More sharing options...
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