Guesses about Gear Ratios and Wheel Torque

[Deslock]

I figured this thread would've died long ago when the ratios were revealed.

143 MPH makes more sense as a top speed than the report of it topping out in 5th (as there really ought to be enough power in 6th to get above 140).

The calculated tire diameter is 24.6", but it's less when loaded down and changes with speed. If 5th tops out at 131, and if you need to upshift to 3rd before 60, the actual diameter would be around 24.3" (though it might be a tad smaller at 60 MPH and higher at 131 MPH). I used 24.31" for this table:

RPM     1st      2nd     3rd      4th     5th      6th
2500    12.2    20.2    28.6    36.4    44.1    57.5
2700    13.1    21.8    30.9    39.3    47.6    62.1
2900    14.1    23.4    33.2    42.2    51.2    66.7
3100    15.1    25.0    35.5    45.1    54.7    71.3
3300    16.1    26.6    37.8    48.0    58.2    75.9
3500    17.0    28.2    40.1    50.9    61.7    80.5
3700    18.0    29.8    42.4    53.8    65.3    85.1
3900    19.0    31.4    44.6    56.7    68.8    89.7
4100    19.9    33.1    46.9    59.6    72.3    94.3
4300    20.9    34.7    49.2    62.5    75.8    98.9
4500    21.9    36.3    51.5    65.4    79.4    103.5
4700    22.9    37.9    53.8    68.3    82.9    108.1
4900    23.8    39.5    56.1    71.3    86.4    112.7
5100    24.8    41.1    58.4    74.2    90.0    117.3
5300    25.8    42.7    60.7    77.1    93.5    121.9
5500    26.8    44.3    63.0    80.0    97.0    126.5
5700    27.7    46.0    65.2    82.9    100.5   131.1
5900    28.7    47.6    67.5    85.8    104.1   135.7
6100    29.7    49.2    69.8    88.7    107.6   140.3
6300    30.6    50.8    72.1    91.6    111.1   144.9
6500    31.6    52.4    74.4    94.5    114.7   -
6700    32.6    54.0    76.7    97.4    118.2   -
6900    33.6    55.6    79.0    100.3   121.7   -
7100    34.5    57.2    81.3    103.2   125.2   -
7300    35.5    58.9    83.6    106.2   128.8   -
7400    36.0    59.7    84.7    107.6   130.5   -

[serialk11r]

I don't think tires lose diameter as they're loaded, because the very outer strip of rubber is what's rolling on the ground and it's not going to deform much, but I think you can't go off tire width * aspect ratio + rim diameter, apparently there are charts with the correct rolling diameters of each tire size but I haven't seen them before. 24.3 is what I heard was the correct diameter though.

This is kind of interesting, it appears to hit top speed around its 6th gear torque peak. Still, I'd rather give up 10mph top speed for better fuel economy on the highway.

[Allch Chcar]

If you go to a place like tirerack and look up the tire they give the RPM @60mph loaded. I've found it to be around 3% more RPMs than calculated.

Deslock, can you output numbers or did you do that by hand? I'd like to see auto vs manual and even compare with 3.727 gears if you could do that easier than me.

[carbonBLUE]

Originally Posted by Deslock

I figured this thread would've died long ago when the ratios were revealed.

143 MPH makes more sense as a top speed than the report of it topping out in 5th (as there really ought to be enough power in 6th to get above 140).

The calculated tire diameter is 24.6", but it's less when loaded down and changes with speed. If 5th tops out at 131, and if you need to upshift to 3rd before 60, the actual diameter would be around 24.3" (though it might be a tad smaller at 60 MPH and higher at 131 MPH). I used 24.31" for this table:

RPM     1st      2nd     3rd      4th     5th      6th
2500    12.2    20.2    28.6    36.4    44.1    57.5
2700    13.1    21.8    30.9    39.3    47.6    62.1
2900    14.1    23.4    33.2    42.2    51.2    66.7
3100    15.1    25.0    35.5    45.1    54.7    71.3
3300    16.1    26.6    37.8    48.0    58.2    75.9
3500    17.0    28.2    40.1    50.9    61.7    80.5
3700    18.0    29.8    42.4    53.8    65.3    85.1
3900    19.0    31.4    44.6    56.7    68.8    89.7
4100    19.9    33.1    46.9    59.6    72.3    94.3
4300    20.9    34.7    49.2    62.5    75.8    98.9
4500    21.9    36.3    51.5    65.4    79.4    103.5
4700    22.9    37.9    53.8    68.3    82.9    108.1
4900    23.8    39.5    56.1    71.3    86.4    112.7
5100    24.8    41.1    58.4    74.2    90.0    117.3
5300    25.8    42.7    60.7    77.1    93.5    121.9
5500    26.8    44.3    63.0    80.0    97.0    126.5
5700    27.7    46.0    65.2    82.9    100.5   131.1
5900    28.7    47.6    67.5    85.8    104.1   135.7
6100    29.7    49.2    69.8    88.7    107.6   140.3
6300    30.6    50.8    72.1    91.6    111.1   144.9
6500    31.6    52.4    74.4    94.5    114.7   -
6700    32.6    54.0    76.7    97.4    118.2   -
6900    33.6    55.6    79.0    100.3   121.7   -
7100    34.5    57.2    81.3    103.2   125.2   -
7300    35.5    58.9    83.6    106.2   128.8   -
7400    36.0    59.7    84.7    107.6   130.5   -

redline is at 7450 rpms so 60mph is possible!

[Deslock]

Originally Posted by carbonBLUE

redline is at 7450 rpms so 60mph is possible!

That's still unknown. I picked those numbers as a middle ground between Insideline's report that the rev limiter in 2nd kicks in at 59.2, and serialk11r's comment that 5th maxes out at ~131.

In retrospect, serialk11r probably based 5th maxing out at 131 on my comment earlier in the thread (note in that in that same comment, I had written that it hits 60 MPH in 2nd). Tire deformation is such that it'll have a higher rolling radius at 131 MPH than at 59.2 MPH, but I don't know the formula.

Maybe 2nd does top out at 59.2 MPH, or maybe Insideline's tires were slightly deflated, or maybe Insideline's results were slightly off due to a mishap with their testing equipment. Who knows? I started this thread because I was curious about gear ratios in general, but I don't care if 2nd tops out at 59.2 or 60.8 MPH. But FWIW, GT5 lets me get to 60 in 2nd gear

Originally Posted by Allch Chcar

Deslock, can you output numbers or did you do that by hand? I'd like to see auto vs manual and even compare with 3.727 gears if you could do that easier than me.

Since we don't know the story regarding rolling radius, here are the two extremes for all three transmissions (again how tire deformation varies with speed is not accounted for):

6MT, DR 3.727, Dia 23.975"

RPM	1st	2nd	3rd	4th	5th	6th
1400	7.4	12.2	17.4	22.1	26.8	34.9
1600	8.4	14.0	19.9	25.2	30.6	39.9
1800	9.5	15.7	22.4	28.4	34.4	44.9
2000	10.6	17.5	24.8	31.6	38.3	49.9
2200	11.6	19.2	27.3	34.7	42.1	54.9
2400	12.7	21.0	29.8	37.9	45.9	59.9
2600	13.7	22.7	32.3	41.0	49.8	64.9
2800	14.8	24.5	34.8	44.2	53.6	69.9
3000	15.8	26.2	37.3	47.3	57.4	74.9
3200	16.9	28.0	39.7	50.5	61.2	79.8
3400	17.9	29.7	42.2	53.6	65.1	84.8
3600	19.0	31.5	44.7	56.8	68.9	89.8
3800	20.1	33.2	47.2	60.0	72.7	94.8
4000	21.1	35.0	49.7	63.1	76.5	99.8
4200	22.2	36.7	52.2	66.3	80.4	104.8
4400	23.2	38.5	54.6	69.4	84.2	109.8
4600	24.3	40.2	57.1	72.6	88.0	114.8
4800	25.3	42.0	59.6	75.7	91.9	119.8
5000	26.4	43.7	62.1	78.9	95.7	124.8
5200	27.4	45.5	64.6	82.0	99.5	129.7
5400	28.5	47.2	67.1	85.2	103.3	134.7
5600	29.6	49.0	69.5	88.4	107.2	139.7
5800	30.6	50.7	72.0	91.5	111.0	144.7
6000	31.7	52.5	74.5	94.7	114.8	149.7
6200	32.7	54.2	77.0	97.8	118.7	154.7
6400	33.8	56.0	79.5	101.0	122.5	159.7
6600	34.8	57.7	82.0	104.1	126.3	164.7
6800	35.9	59.5	84.4	107.3	130.1	169.7
7000	36.9	61.2	86.9	110.4	134.0	174.7
7200	38.0	63.0	89.4	113.6	137.8	179.6
7400	39.1	64.7	91.9	116.7	141.6	184.6
7450	39.3	65.2	92.5	117.5	142.6	185.9

6MT, DR 3.727, Dia 24.6"

RPM	1st	2nd	3rd	4th	5th	6th
1400	7.6	12.6	17.8	22.7	27.5	35.8
1600	8.7	14.4	20.4	25.9	31.4	41.0
1800	9.7	16.2	22.9	29.1	35.3	46.1
2000	10.8	17.9	25.5	32.4	39.3	51.2
2200	11.9	19.7	28.0	35.6	43.2	56.3
2400	13.0	21.5	30.6	38.9	47.1	61.4
2600	14.1	23.3	33.1	42.1	51.1	66.6
2800	15.2	25.1	35.7	45.3	55.0	71.7
3000	16.2	26.9	38.2	48.6	58.9	76.8
3200	17.3	28.7	40.8	51.8	62.8	81.9
3400	18.4	30.5	43.3	55.0	66.8	87.0
3600	19.5	32.3	45.9	58.3	70.7	92.2
3800	20.6	34.1	48.4	61.5	74.6	97.3
4000	21.7	35.9	51.0	64.8	78.5	102.4
4200	22.7	37.7	53.5	68.0	82.5	107.5
4400	23.8	39.5	56.1	71.2	86.4	112.6
4600	24.9	41.3	58.6	74.5	90.3	117.8
4800	26.0	43.1	61.2	77.7	94.3	122.9
5000	27.1	44.9	63.7	80.9	98.2	128.0
5200	28.2	46.7	66.3	84.2	102.1	133.1
5400	29.2	48.5	68.8	87.4	106.0	138.2
5600	30.3	50.3	71.4	90.7	110.0	143.4
5800	31.4	52.1	73.9	93.9	113.9	148.5
6000	32.5	53.8	76.5	97.1	117.8	153.6
6200	33.6	55.6	79.0	100.4	121.7	158.7
6400	34.7	57.4	81.6	103.6	125.7	163.8
6600	35.7	59.2	84.1	106.8	129.6	169.0
6800	36.8	61.0	86.6	110.1	133.5	174.1
7000	37.9	62.8	89.2	113.3	137.5	179.2
7200	39.0	64.6	91.7	116.6	141.4	184.3
7400	40.1	66.4	94.3	119.8	145.3	189.5
7450	40.3	66.9	94.9	120.6	146.3	190.7

6MT, DR 4.1, Dia 23.975"

RPM	1st	2nd	3rd	4th	5th	6th
1400	6.7	11.1	15.8	20.1	24.4	31.8
1600	7.7	12.7	18.1	22.9	27.8	36.3
1800	8.6	14.3	20.3	25.8	31.3	40.8
2000	9.6	15.9	22.6	28.7	34.8	45.4
2200	10.6	17.5	24.8	31.6	38.3	49.9
2400	11.5	19.1	27.1	34.4	41.8	54.4
2600	12.5	20.7	29.4	37.3	45.2	59.0
2800	13.4	22.3	31.6	40.2	48.7	63.5
3000	14.4	23.9	33.9	43.0	52.2	68.0
3200	15.4	25.4	36.1	45.9	55.7	72.6
3400	16.3	27.0	38.4	48.8	59.1	77.1
3600	17.3	28.6	40.6	51.6	62.6	81.7
3800	18.2	30.2	42.9	54.5	66.1	86.2
4000	19.2	31.8	45.2	57.4	69.6	90.7
4200	20.2	33.4	47.4	60.2	73.1	95.3
4400	21.1	35.0	49.7	63.1	76.5	99.8
4600	22.1	36.6	51.9	66.0	80.0	104.3
4800	23.0	38.2	54.2	68.8	83.5	108.9
5000	24.0	39.8	56.4	71.7	87.0	113.4
5200	24.9	41.3	58.7	74.6	90.5	117.9
5400	25.9	42.9	61.0	77.4	93.9	122.5
5600	26.9	44.5	63.2	80.3	97.4	127.0
5800	27.8	46.1	65.5	83.2	100.9	131.6
6000	28.8	47.7	67.7	86.1	104.4	136.1
6200	29.7	49.3	70.0	88.9	107.9	140.6
6400	30.7	50.9	72.3	91.8	111.3	145.2
6600	31.7	52.5	74.5	94.7	114.8	149.7
6800	32.6	54.1	76.8	97.5	118.3	154.2
7000	33.6	55.7	79.0	100.4	121.8	158.8
7200	34.5	57.2	81.3	103.3	125.3	163.3
7400	35.5	58.8	83.5	106.1	128.7	167.8
7450	35.7	59.2	84.1	106.8	129.6	169.0

6MT, DR 4.1, Dia 24.6"

RPM	1st	2nd	3rd	4th	5th	6th
1400	6.9	11.4	16.2	20.6	25.0	32.6
1600	7.9	13.1	18.5	23.5	28.6	37.2
1800	8.9	14.7	20.9	26.5	32.1	41.9
2000	9.8	16.3	23.2	29.4	35.7	46.5
2200	10.8	17.9	25.5	32.4	39.3	51.2
2400	11.8	19.6	27.8	35.3	42.8	55.9
2600	12.8	21.2	30.1	38.3	46.4	60.5
2800	13.8	22.8	32.4	41.2	50.0	65.2
3000	14.8	24.5	34.8	44.1	53.5	69.8
3200	15.8	26.1	37.1	47.1	57.1	74.5
3400	16.7	27.7	39.4	50.0	60.7	79.1
3600	17.7	29.4	41.7	53.0	64.3	83.8
3800	18.7	31.0	44.0	55.9	67.8	88.4
4000	19.7	32.6	46.3	58.9	71.4	93.1
4200	20.7	34.3	48.7	61.8	75.0	97.7
4400	21.7	35.9	51.0	64.7	78.5	102.4
4600	22.6	37.5	53.3	67.7	82.1	107.1
4800	23.6	39.2	55.6	70.6	85.7	111.7
5000	24.6	40.8	57.9	73.6	89.2	116.4
5200	25.6	42.4	60.2	76.5	92.8	121.0
5400	26.6	44.1	62.6	79.5	96.4	125.7
5600	27.6	45.7	64.9	82.4	100.0	130.3
5800	28.6	47.3	67.2	85.4	103.5	135.0
6000	29.5	48.9	69.5	88.3	107.1	139.6
6200	30.5	50.6	71.8	91.2	110.7	144.3
6400	31.5	52.2	74.1	94.2	114.2	148.9
6600	32.5	53.8	76.5	97.1	117.8	153.6
6800	33.5	55.5	78.8	100.1	121.4	158.3
7000	34.5	57.1	81.1	103.0	124.9	162.9
7200	35.4	58.7	83.4	106.0	128.5	167.6
7400	36.4	60.4	85.7	108.9	132.1	172.2
7450	36.7	60.8	86.3	109.6	133.0	173.4

6AT, Dia 23.975"

RPM	1st	2nd	3rd	4th	5th	6th
1400	6.9	11.8	17.3	24.4	34.2	41.8
1600	7.9	13.5	19.8	27.8	39.0	47.8
1800	8.9	15.2	22.3	31.3	43.9	53.8
2000	9.8	16.9	24.8	34.8	48.8	59.8
2200	10.8	18.6	27.3	38.3	53.7	65.8
2400	11.8	20.3	29.7	41.8	58.6	71.7
2600	12.8	22.0	32.2	45.2	63.4	77.7
2800	13.8	23.6	34.7	48.7	68.3	83.7
3000	14.8	25.3	37.2	52.2	73.2	89.7
3200	15.7	27.0	39.7	55.7	78.1	95.7
3400	16.7	28.7	42.1	59.1	83.0	101.6
3600	17.7	30.4	44.6	62.6	87.8	107.6
3800	18.7	32.1	47.1	66.1	92.7	113.6
4000	19.7	33.8	49.6	69.6	97.6	119.6
4200	20.7	35.5	52.0	73.1	102.5	125.5
4400	21.6	37.2	54.5	76.5	107.4	131.5
4600	22.6	38.8	57.0	80.0	112.2	137.5
4800	23.6	40.5	59.5	83.5	117.1	143.5
5000	24.6	42.2	62.0	87.0	122.0	149.5
5200	25.6	43.9	64.4	90.5	126.9	155.4
5400	26.6	45.6	66.9	93.9	131.8	161.4
5600	27.5	47.3	69.4	97.4	136.6	167.4
5800	28.5	49.0	71.9	100.9	141.5	173.4
6000	29.5	50.7	74.3	104.4	146.4	179.3
6200	30.5	52.4	76.8	107.9	151.3	185.3
6400	31.5	54.0	79.3	111.3	156.2	191.3
6600	32.5	55.7	81.8	114.8	161.0	197.3
6800	33.4	57.4	84.3	118.3	165.9	203.3
7000	34.4	59.1	86.7	121.8	170.8	209.2
7200	35.4	60.8	89.2	125.3	175.7	215.2
7400	36.4	62.5	91.7	128.7	180.6	221.2
7450	36.6	62.9	92.3	129.6	181.8	222.7

6AT, Dia 24.6"

RPM	1st	2nd	3rd	4th	5th	6th
1400	7.1	12.1	17.8	25.0	35.0	42.9
1600	8.1	13.9	20.3	28.6	40.1	49.1
1800	9.1	15.6	22.9	32.1	45.1	55.2
2000	10.1	17.3	25.4	35.7	50.1	61.3
2200	11.1	19.1	28.0	39.3	55.1	67.5
2400	12.1	20.8	30.5	42.8	60.1	73.6
2600	13.1	22.5	33.1	46.4	65.1	79.7
2800	14.1	24.3	35.6	50.0	70.1	85.9
3000	15.1	26.0	38.1	53.5	75.1	92.0
3200	16.1	27.7	40.7	57.1	80.1	98.1
3400	17.2	29.5	43.2	60.7	85.1	104.3
3600	18.2	31.2	45.8	64.3	90.1	110.4
3800	19.2	32.9	48.3	67.8	95.1	116.5
4000	20.2	34.7	50.9	71.4	100.1	122.7
4200	21.2	36.4	53.4	75.0	105.1	128.8
4400	22.2	38.1	55.9	78.5	110.2	134.9
4600	23.2	39.9	58.5	82.1	115.2	141.1
4800	24.2	41.6	61.0	85.7	120.2	147.2
5000	25.2	43.3	63.6	89.2	125.2	153.4
5200	26.2	45.1	66.1	92.8	130.2	159.5
5400	27.2	46.8	68.7	96.4	135.2	165.6
5600	28.3	48.5	71.2	100.0	140.2	171.8
5800	29.3	50.3	73.7	103.5	145.2	177.9
6000	30.3	52.0	76.3	107.1	150.2	184.0
6200	31.3	53.7	78.8	110.7	155.2	190.2
6400	32.3	55.5	81.4	114.2	160.2	196.3
6600	33.3	57.2	83.9	117.8	165.2	202.4
6800	34.3	58.9	86.5	121.4	170.2	208.6
7000	35.3	60.7	89.0	124.9	175.2	214.7
7200	36.3	62.4	91.5	128.5	180.3	220.8
7400	37.3	64.1	94.1	132.1	185.3	227.0
7450	37.6	64.6	94.7	133.0	186.5	228.5

[Allch Chcar]

Going off of the tirerack specs for a similar tire, the RPM@60 is 844. Tire circumference is about 24.7"

Strangely the actual stock tires used don't have these specs, probably not that far off though.

How did you make those BTW?

[serialk11r]

Actually, I just google searched, and what do you know, the first link is to ft86club.com...
-_-

Apparently the correct rolling circumference for a 215/45/17 tire is about 23.9 inches, so I guess there wasn't a mistake.
Funny thing is, 205/55/16s probably hit 60 in 2nd lol. Another reason to want the 16" rims, not only do they look better and tires cost less, but you can brag about a faster 0-60!

The rolling circumference isn't going to change from load. The tire may look deformed, but the outer strip of rubber that is the tread will not have changed overall length. However I'm not sure what's going on because no matter how section width is measured the aspect ratio is going off distance from rim to tread...the person who said 23.9 inches got it from an official European tire regulatory thingy website, and it seems to be in line with the observation that 2nd gear doesn't hit 60mph. Or maybe their GPS tracking was too slow, but if they use it on other cars just fine doesn't seem like it would be the case.

[Allch Chcar]

The measurements for a 215/45/17 tire just by doing the math is 24.618" so there's no way it's 23.9"

Check my math.

[Deslock]

Originally Posted by Allch Chcar

How did you make those BTW?

spreadsheet

60 * tire_circ_feet * RPM / (gear_ratio * DR * 5280)

[Want.FR-S]

Being in Canada I am more used to KM/H rather than inch/feet/mile. I also use spreadsheet to do these calculation, and my results are closed to what Deslock provide.

Some points;

1. Tire diameter for 215/45/17 is 625.30 mm / 24.62 inch *without* considering the deformation. I do not know how that is determined but a 0.7" deformation could be significant.
2. The default tire selection is 205/55/16 with diameter 631.90 mm / 24.88 inch. So if you swap this tire with the 17" one from OEM you could reach 60 mph in 2nd gear with larger circumference.
3. Based on its gear ratio, the automatic should be able to hit 60 mph in second gear. That could mean a faster 0-60 time.
4. According to the Subaru website in Japan, if the care comes with 16 in wheel, its final drive ratio is *different*. I wonder if they have to use a different final drive ratio to compensate the difference of circumference between the 16" and 17" wheels.

That's it for now.

[Want.FR-S]

Another note: does anyone knows why the top speed is at 145 mph? Was that government limited or simply not enough power to go higher? Based on the spreadsheet, with 3.727 final drive ratio, one could reach 300 KM/hr at 7200 RPM. This could be a contender in the Tokyo Midnight Wangan run.

[Deslock]

Originally Posted by Want.FR-S

Another note: does anyone knows why the top speed is at 145 mph? Was that government limited or simply not enough power to go higher? Based on the spreadsheet, with 3.727 final drive ratio, one could reach 300 KM/hr at 7200 RPM. This could be a contender in the Tokyo Midnight Wangan run.

No way would it hit 300 km/hr. Most of my tables don't reflect top speed, which is reportedly drag limited.

Originally Posted by Want.FR-S

Being in Canada I am more used to KM/H rather than inch/feet/mile. I also use spreadsheet to do these calculation, and my results are closed to what Deslock provide.

Some points;

1. Tire diameter for 215/45/17 is 625.30 mm / 24.62 inch *without* considering the deformation. I do not know how that is determined but a 0.7" deformation could be significant.
2. The default tire selection is 205/55/16 with diameter 631.90 mm / 24.88 inch. So if you swap this tire with the 17" one from OEM you could reach 60 mph in 2nd gear with larger circumference.
3. Based on its gear ratio, the automatic should be able to hit 60 mph in second gear. That could mean a faster 0-60 time.
4. According to the Subaru website in Japan, if the care comes with 16 in wheel, its final drive ratio is *different*. I wonder if they have to use a different final drive ratio to compensate the difference of circumference between the 16" and 17" wheels.

That's it for now.

There's got to be some tire deformation, but 0.7" is higher than I'd expect for 215/45R-17 (maybe I'm wrong).

You brought up a good point regarding the 16" rims... if those are standard on the cars with a 3.727 DR, then (ignoring deformation):

6MT, DR 3.727, Dia 24.88" (205/55R-16):

RPM	1st	2nd	3rd	4th	5th	6th
7450	40.8	67.6	96.0	122.0	-	-

I had intended to clean up my spreadsheet and post it on google docs, but never got around to it.

[Allch Chcar]

Originally Posted by Deslock

spreadsheet

Oh yeah. <.> *derp*

Where did I put my gear ratio spreadsheet...

[serialk11r]

Tire deformation is going to be very small if you think about it. The rolling circumference of the tire is the length of the tread. The tread itself is reinforced with steel underneath, so only the surface can experience minor stretching. The rubber part of the tire is well under an inch thick.

So the question is, why does some official tire spec regulatory body in Europe say a 215/45/17 tire is 23.9" when the way tires are measured implies it's 24.6"? Why is the car not hitting 60mph in 2nd gear if the tire is indeed 24.6"?