RogerB Posted November 12, 2010 Share Posted November 12, 2010 So, stock tires on an LGT are 215/45-17. Stock tires on the Spec B are 215/45-18. These tires have notionally the same sidewall height, making the Spec B wheel-tire package larger in overall diameter. Why doesn't the Spec B come with, say, 215/40-18, or 225/35-18? Link to comment Share on other sites More sharing options...
RogerB Posted November 12, 2010 Author Share Posted November 12, 2010 Is the speedo calibrated differently between the Spec B and the standard LGT? Link to comment Share on other sites More sharing options...
burnout8488 Posted November 12, 2010 Share Posted November 12, 2010 225/40-18 is what it SHOULD be, I believe. I've always wondered this too. Maybe this decision was made to preserve some sort of ride comfort on models with 18" rims. Link to comment Share on other sites More sharing options...
IanB Posted November 12, 2010 Share Posted November 12, 2010 Using this tool: http://www.miata.net/garage/tirecalc.html It looks like the spec B is 4.1% different than the LGT, within the margin of error I'd say. Link to comment Share on other sites More sharing options...
wpmarky Posted November 12, 2010 Share Posted November 12, 2010 45 profile is more comfortable. Yes the speedo is calibrated differently. Link to comment Share on other sites More sharing options...
vr4Legacy Posted November 12, 2010 Share Posted November 12, 2010 TireRack says 225/40/18 are the optional for us non-Spec B owner. But also says 215/45/18 for Spec-B Maybe Subaru put larger tires to compensate for the shear force and extra G's the Spec B generates under acceleration? I hear that Unicorn under the hood also causes more strain on the tires.... Link to comment Share on other sites More sharing options...
dmanaenk Posted November 12, 2010 Share Posted November 12, 2010 Spec.b owners need that extra half inch of height to look down upon plane-jane lgt owners. 666 Link to comment Share on other sites More sharing options...
ttnio Posted November 12, 2010 Share Posted November 12, 2010 More sidewall area more comfort.... Link to comment Share on other sites More sharing options...
lucas569 Posted November 12, 2010 Share Posted November 12, 2010 Spec.b owners need that extra half inch of height to look down upon plane-jane lgt owners. i thought it was to keep the sonic boom in check? Link to comment Share on other sites More sharing options...
spec.B Dream Posted November 12, 2010 Share Posted November 12, 2010 Isn't the speed sensor a part of the tranny? They would have to calibrate it anyway since it is a different tranny, so tire diameter really doesn't matter. Link to comment Share on other sites More sharing options...
PhilT Posted November 12, 2010 Share Posted November 12, 2010 Isn't the speed sensor a part of the tranny? They would have to calibrate it anyway since it is a different tranny, so tire diameter really doesn't matter. what connects the tranny to the road ? Double Award Winning Legacy GT Wagon Link to comment Share on other sites More sharing options...
GTTuner Posted November 12, 2010 Share Posted November 12, 2010 I think the gearing is different anyway (6 speed)? Link to comment Share on other sites More sharing options...
whitetiger Posted November 12, 2010 Share Posted November 12, 2010 ^yes, but remember, the 06 spec b had the same gearing and trans as the regular LGT. Link to comment Share on other sites More sharing options...
whitetiger Posted November 12, 2010 Share Posted November 12, 2010 Isn't the speed sensor a part of the tranny? They would have to calibrate it anyway since it is a different tranny, so tire diameter really doesn't matter. speed sensor on our cars is the abs/wheel sensor. it would still have to be calibrated in the overall wheel diameter was changed significantly. Link to comment Share on other sites More sharing options...
vr4Legacy Posted November 12, 2010 Share Posted November 12, 2010 i think the speed sensor argument was meant as "they are using a different tranny for the Spec-B, therefore they will need to use a different speed sensor and calibrate it irregardless, so whatever tire size they pick won't matter, so long as it's the same for all Spec-B's" I'm guessing the larger sidewall is to compensate for the firmer suspension a little bit. Link to comment Share on other sites More sharing options...
dmanaenk Posted November 12, 2010 Share Posted November 12, 2010 i thought it was to keep the sonic boom in check? No, that's another issue. It's easier to lift off the ground in the spec.b, since the pressure under the car is higher due to higher clearance. 666 Link to comment Share on other sites More sharing options...
RogerB Posted November 15, 2010 Author Share Posted November 15, 2010 It seems wrong-headed to me. I'm thinking specifically of the '06, which is geared the same as the regular GT. The only reasons to go up in wheel size would be to clear larger brakes and/or to allow a shorter sidewall tire for better turn-in and more precise control, etc. The way Subaru did it would actually make the car slower. Taller gearing, more weight. No increase in power. Marketing BS and jewelry bragging rights. Link to comment Share on other sites More sharing options...
Scooter Posted November 15, 2010 Share Posted November 15, 2010 Pretty much. They wanted to go with 18" wheels for marketing reasons, but didn't want to sacrifice ride quality, so they stayed with the same sidewall size on the tires. Not that big of deal, though; I actually wouldn't mind the taller gearing. Seek first to understand, then to be understood. In other words: SEARCH before you post! Link to comment Share on other sites More sharing options...
spec.B Dream Posted November 15, 2010 Share Posted November 15, 2010 I'd rather have 17s. Does the turning radius suck on all 4th gen Legacies, or did they have to shorten the turns lock-to-lock to accommodate the larger wheels? Of all cars, SUVs, and trucks (including U-Haul), my spec.B has by far the worst turning radius. I need to cross a full 3 lanes to make a u-turn. Link to comment Share on other sites More sharing options...
Scooter Posted November 15, 2010 Share Posted November 15, 2010 Strange; maybe they did change that for the B's...?? My car has a nice tight turning radius; much much better than the gf's smaller RSX. Seek first to understand, then to be understood. In other words: SEARCH before you post! Link to comment Share on other sites More sharing options...
Mobius118 Posted November 15, 2010 Share Posted November 15, 2010 Agreed, my 05 is just fine in the turning radius department. Not as good as my WRX was, but nowhere near as bad as the S60R I was debating on buying before I got the LGT. I was also half contemplating getting a set of Spec B. wheels that were being offered at the same time, but not at 28lbs apiece. Link to comment Share on other sites More sharing options...
eldiablo Posted November 15, 2010 Share Posted November 15, 2010 I suppose it's all relative. The turning radius on my LGT seems not-so-tight compared to the Volvo S40 I was driving last week. My VB Garage... Pumping the air back into despair Link to comment Share on other sites More sharing options...
Mobius118 Posted November 15, 2010 Share Posted November 15, 2010 That's true, my uncle's S40 is tighter than the LGT (maybe with the R it was the awd and the active chassis that resulted in a wide turning radius) Link to comment Share on other sites More sharing options...
vr4Legacy Posted November 15, 2010 Share Posted November 15, 2010 mine was tight when I first got her, but has since loosened up, probably from all the hard repititive driving and pushing from all angles..... wait wait we're talking turning radii aren't we.... In that case, I am happy with my LGT, plenty tight enough for my needs Link to comment Share on other sites More sharing options...
naimouasta Posted November 15, 2010 Share Posted November 15, 2010 i think subaru picked those sizes because they are the more popular tire size given the dimension of the wheels. for the GT, 17X7, i think a 225 would be just a smidge too wide, which is why they went with a 215. same thing for the spec b with 18x7. as for sidewall, it was probably for comfort and popular sizes. and i think the speed sensors are the same. the margin of error should cover all tire sizes. plus when i went to 235/40/18 vs the stock 2.5i 205/50/17, my speedometer is actually more accurate now according to my GPS. Link to comment Share on other sites More sharing options...
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