[HondaBre]

I did not find answer on this forum or any other place so am asking:

Does anybody know what is gear ratio for:
- 1.5t - simulated 7 gears CVT and
- 2.0t - real 10 gears.

I was driving 100km/h in 2.0 Touring and RPM was unbelievable 1500 !

 

[Baldeagle]

That is right. You can do the math for proof. According to https://automobiles.honda.com/accord-sedan#, the gear ratio for 10th gear is .517 on a 3.55 final drive. That means in 10th gear, the engine spins 1.835 times every time the wheel spins one time.

The tires are 235/40-19s. That gives them a diameter of 26.40” and a circumference of 82.93” or 6.91 feet. One mile is exactly 5,280 feet. For that tire to travel 5,280 feet, it must spin exactly 764 times. One mile per minute is 60 miles per hour, which is almost 100 km/hr. That means to travel at 60 mph the wheel must spin at 764 rpm. We know that the engine must spin 1.835 times for each rotation of the wheel. Therefore at 60 mph, or 764 rpm for the tire, the engine must spin at 1,402 rpm. At 62.5 mph it should be 1,460 rpm. That’s pretty close to the 1,500 rpm you saw on the tach. And if you have 17" wheels, those smaller 225/50-17 tires (25.86" diameter) would explain the very slight difference.

So yes, the 10AT cranks about 1,500 rpm at 60 mph. The CVT can theoretically go lower if it locks into its top ratio. The CVT's ratio spread is 2.645 to .405 on a 3.28 final drive. If you trust Honda's information and do the math, it should crank about 1,014 rpm at 60 mph. But something tells me the CVT never locks into that max ratio.

 

[NH Guy]

My wife's 2.0 10AT EX-L with 17" wheels is turning just 1900 RPM at an indicated 80 MPH in 10th gear, so your number looks very close.

 

[HondaBre]

Baldeagle, this is Amazing explanation. Never thought of such calculation. Thank you.

Would you be able to advise which (not brand but dimensions) 18" wheels and tires are optimal choice to downsize from 19" to 18". Or even 17"? Would you do that at all? As I keep my vehicles for a long time, I am not keen to change tires every few years and prefer 'lush' than 'sporty' ride.
Tire math is black box for me and frankly speaking I am not that enthusiast to understand all those numbers regarding wheels/tires.

 

[AlanTheBeastV2]

So yes, the 10AT cranks about 1,500 rpm at 60 mph. The CVT can theoretically go lower if it locks into its top ratio. The CVT's ratio spread is 2.645 to .405 on a 3.28 final drive. If you trust Honda's information and do the math, it should crank about 1,014 rpm at 60 mph. But something tells me the CVT never locks into that max ratio.

1014 RPM at 60 mph would be lugging hard. Would be crap for turbo gas volume as well.

My 2.4 (Accord automatic) cranks (IIRC) a little over 2100 RPM at 120 km/hr (~75 mph) and seems happy. I'd expect the 1.5T to spin a little quicker at that speed for optimum engine contentment.

 

[Baldeagle]

Baldeagle, this is Amazing explanation. Never thought of such calculation. Thank you.

Would you be able to advise which (not brand but dimensions) 18" wheels and tires are optimal choice to downsize from 19" to 18". Or even 17"? Would you do that at all? As I keep my vehicles for a long time, I am not keen to change tires every few years and prefer 'lush' than 'sporty' ride.
Tire math is black box for me and frankly speaking I am not that enthusiast to understand all those numbers regarding wheels/tires.

• A stock 235/40-19 tire has a 26.40” diameter. However a stock 225/50-17 tire has a diameter of 25.86”, which is about 2% smaller. This is not an exact science.
• A 235/45-18 tire has a 26.33” diameter which is about .28% smaller than the 19” tire and is probably the best sized 18” tire for an Accord.
• A 245/40-18 tire has a 25.72” diameter, which is about 2.6% smaller than the 235/40-19.
• A 245/45-18 tire has a 26.68”diameter, which is about 1.06% larger. That one could potentially work, but I think the 235/45-18 is best. If it were my car that is what I would select.

 

[jwtarbaj]

That is right. You can do the math for proof. According to https://automobiles.honda.com/accord-sedan#, the gear ratio for 10th gear is .517 on a 3.55 final drive. That means in 10th gear, the engine spins 1.835 times every time the wheel spins one time.

The tires are 235/40-19s. That gives them a diameter of 26.40” and a circumference of 82.93” or 6.91 feet. One mile is exactly 5,280 feet. For that tire to travel 5,280 feet, it must spin exactly 764 times. One mile per minute is 60 miles per hour, which is almost 100 km/hr. That means to travel at 60 mph the wheel must spin at 764 rpm. We know that the engine must spin 1.835 times for each rotation of the wheel. Therefore at 60 mph, or 764 rpm for the tire, the engine must spin at 1,402 rpm. At 62.5 mph it should be 1,460 rpm. That’s pretty close to the 1,500 rpm you saw on the tach. And if you have 17" wheels, those smaller 225/50-17 tires (25.86" diameter) would explain the very slight difference.

So yes, the 10AT cranks about 1,500 rpm at 60 mph. The CVT can theoretically go lower if it locks into its top ratio. The CVT's ratio spread is 2.645 to .405 on a 3.28 final drive. If you trust Honda's information and do the math, it should crank about 1,014 rpm at 60 mph. But something tells me the CVT never locks into that max ratio.

Every CVT I've seen specs on always has a very high axle ratio.

You got a oops there:

Continuously Variable Transmission (CVT) with Sport Mode:
Ratio Range:2.645 ~ 0.405
Final Drive:5.36

https://owners.honda.com/vehicles/information/2018/Accord-Sedan/specs#mid^CV1F5JJNW

 

[meowcat]

That is right. You can do the math for proof. According to https://automobiles.honda.com/accord-sedan#, the gear ratio for 10th gear is .517 on a 3.55 final drive. That means in 10th gear, the engine spins 1.835 times every time the wheel spins one time.

The tires are 235/40-19s. That gives them a diameter of 26.40” and a circumference of 82.93” or 6.91 feet. One mile is exactly 5,280 feet. For that tire to travel 5,280 feet, it must spin exactly 764 times. One mile per minute is 60 miles per hour, which is almost 100 km/hr. That means to travel at 60 mph the wheel must spin at 764 rpm. We know that the engine must spin 1.835 times for each rotation of the wheel. Therefore at 60 mph, or 764 rpm for the tire, the engine must spin at 1,402 rpm. At 62.5 mph it should be 1,460 rpm. That’s pretty close to the 1,500 rpm you saw on the tach. And if you have 17" wheels, those smaller 225/50-17 tires (25.86" diameter) would explain the very slight difference.

So yes, the 10AT cranks about 1,500 rpm at 60 mph. The CVT can theoretically go lower if it locks into its top ratio. The CVT's ratio spread is 2.645 to .405 on a 3.28 final drive. If you trust Honda's information and do the math, it should crank about 1,014 rpm at 60 mph. But something tells me the CVT never locks into that max ratio.

Pure genius.

 

[Baldeagle]

Every CVT I've seen specs on always has a very high axle ratio.

You got a oops there:

Continuously Variable Transmission (CVT) with Sport Mode:
Ratio Range:2.645 ~ 0.405
Final Drive:5.36

https://owners.honda.com/vehicles/information/2018/Accord-Sedan/specs#mid^CV1F5JJNW

Thank you. That makes sense. HOWEVER, I took my info off Honda’s website too. ( https://automobiles.honda.com/accord-sedan#)
Please see attached thumbnails. The 2018 and 2019 Accords show a final drive of 3.238 for the CVT. This is not the first time Honda’s website contained a major error. 1,000 rpm at 60 mph seemed very wrong. If you note, I even qualified my statement by writing:

If you trust Honda's information…

If you crunch the numbers using your 5.36 final drive, the rpm at 60 mph should be about 1,658. That makes MUCH more sense. Thanks again.

Also, my calculations may understate rpm very slightly because it assumes a 235/40-19 tire is perfectly round and therefore exactly 26.40” tall. Even at highway speeds, the tire has a very slight bulge at the bottom and therefore has a diameter less than 26.40”. Real life highway rpm may be slightly higher.
.

 

[HondaBre]

but I think the 235/45-18 is best. If it were my car that is what I would select.

Thank you very much. I will consider wheels of that size.
Now, what size of all-season tires I should look for? I understand they have to be 18" but what about other measurements? Width, etc.?

 

[Baldeagle]

Thank you very much. I will consider wheels of that size.
Now, what size of all-season tires I should look for? I understand they have to be 18" but what about other measurements? Width, etc.?

That information lies in the tire’s description. A 235/45-18 tire is the dimension you want (my opinion). The “18” part tells you the diameter of the tire’s hole is 18” and will only fit on an 18” wheel. The “235/45” part describes the tire. The “235” part means the tire’s width is 235mm. The “45” part is used to describe the sidewall’s height. It’s called the profile. The “45” stands for 45%. That percent is applied to the width of the tire, in this case 235mm. (A tire's sidewall height is the profile times the width. In this case, the sidewall is 45% of 235mm.) If you multiply 235mm by 45%, you get 105.75mm. That means each sidewall is 105.75mm tall. (Remember, there are two sidewalls, the top and bottom.) To get the tire’s diameter, you must multiply 105.75mm by two (211.50mm), convert to inches (8.326”) and add that to the wheel diameter (18”). In this case you get 26.32”.

Within the world of 18” tires, there are many combinations of width and profile. This specific one, a 235/45-18, gives a tire diameter that most closely matches the diameter of a 235/40-19 tire. I hope that helped.

 

[Andrew O]

you may also consider H speed rating vs V specified by Honda, H rating offers softer side wall for this 'lush' ride, I just changed my Michelins V rated to Pirelli H rated, 235/45/18

 

[jwtarbaj]

Thank you. That makes sense. HOWEVER, I took my info off Honda’s website too. ( https://automobiles.honda.com/accord-sedan#)
Please see attached thumbnails. The 2018 and 2019 Accords show a final drive of 3.238 for the CVT. This is not the first time Honda’s website contained a major error. 1,000 rpm at 60 mph seemed very wrong. If you note, I even qualified my statement by writing:



If you crunch the numbers using your 5.36 final drive, the rpm at 60 mph should be about 1,658. That makes MUCH more sense. Thanks again.

Also, my calculations may understate rpm very slightly because it assumes a 235/40-19 tire is perfectly round and therefore exactly 26.40” tall. Even at highway speeds, the tire has a very slight bulge at the bottom and therefore has a diameter less than 26.40”. Real life highway rpm may be slightly higher.
.

Ha so big oops by Honda about their own car :0 Figured it was out of a magazine or review site. I had Nissans before the Accord so I am familiar with their CVTs. All of them have a Final Drive of 5.xx always very high. I assume it helps with acceleration from a stop and the characteristics of a CVT.

 

[HondaBre]

you may also consider H speed rating vs V specified by Honda, H rating offers softer side wall for this 'lush' ride, I just changed my Michelins V rated to Pirelli H rated, 235/45/18

Than you Baldeagle far indispensable wealth of information regarding wheels/tires.

Andrew O - which exact wheels/tires you got and what was the reason for THAT exact set? And what was the charge for the whole set (tax included)?

 

[Andrew O]

Andrew O - which exact wheels/tires you got and what was the reason for THAT exact set? And what was the charge for the whole set (tax included)?

My 2014 Accord Sport 6M came with OEM Michelins MXM4, size 235/45R18 94V, after ~83K km, there were still ok for another ~10K km, in summer conditions, but just returning from Arizona and faced with another two months of winter driving in Calgary, decided to change them to Pirelli CINTURATO P7 ALL SEASON PLUS, 235/45R18 94H, and they have a better rating from TireRack for quietness and for hard ride on poor hwys, I bought them with H speed rating, (210km/hr vs 240km/hr for OEM tires) for softer side wall, and hopefully more comfortable ride, it's difficult to assess benefit right now as we have very cold temperature in Calgary, since I changed them, so tires are now stiff/frozen just from v.low temperature. Bought them from Tire Pirates in Calgary, for $975.32 CAD including GST, installation and balance was free/included in this price, purchased them last year and got also $60 rebate from Pirelli last year, that Pirelli tire at TireRack have higher overall rating than Michelin I had

 

[HondaBre]

1.5T RPM depending on speed

Could somebody be so kind to provide RPM 1.5T is turning at in highest gear ('7'):
90Km/h (~56mil/h)
95Km/h (~60mil/h)
100km/h (~63mil/h)

 

[Baldeagle]

The CVT has a top gear ratio of .405 mated to a 5.36:1 final drive. That means in top gear the engine revolves 2.17 times for each tire revolution. We already know the Accord’s tire must spin about 764 times to travel one mile which implies 764 rpm to travel at 60 mph. To arrive at engine rpm, we multiply the tire's rpm by the gear ratio. Therefore at 60 mph, we multiply 764 tire rpm by 2.17 to arrive at 1,658 engine rpm at 60 mph.

At 56 mph (90 km/h), the engine rpm are 1,547

At 62.5 mph (100 km), the engine rpm are 1,727

 

[HondaBre]

Much appreciate your answer. Learn new things every day!
I was impressed while testing 2.0T when it showed around 1500 RPM going 100km/h.
If 1.5T does around 1,700 RPM I would be really happy as my current 2004 Accord, stick, show around 2,200 RPM at that speed.