Tire size versus RPM's

[NotBudule2]

Right now , in Sport mode , cruising at 40 MPH is equal to exactly 2500 RPM's , if i jump up to 33's (or just a tad smaller) what do you think the RPM's will drop down to ? Or will it even be noticeable?

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[Frenchy]

It will drop, I just don't remember what to exactly. Just remember to calibrate for the different tire size when you do it so the Speedometer and Odometer are accurate.

 

[PltFX4]

Right now , in Sport mode , cruising at 40 MPH is equal to exactly 2500 RPM's , if i jump up to 33's (or just a tad smaller) what do you think the RPM's will drop down to ? Or will it even be noticeable?

Speed versus RPM Calculator

OK, Sport Mode in what gear??

MPH by gear
		My Summers	OEM 18"	32.7"
RPM: 2000​	Gear Ratio	275x55R20​	265/60R18​	285/70R17​
First​	4.696​	10.84​	10.33​	11.11​
Second​	2.985​	17.05​	16.25​	17.47​
Third​	2.146​	23.71​	22.60​	24.31​
Fourth​	1.769​	28.77​	27.41​	29.49​
Fifth​	1.520​	33.48​	31.90​	34.32​
Sixth​	1.275​	39.91​	38.03​	40.91​
Seventh​	1.010​	50.38​	48.01​	51.65​
Eighth​	0.854​	59.59​	56.78​	61.08​
Ninth​	0.689​	73.85​	70.38​	75.71​
Tenth​	0.636​	80.01​	76.25​	82.02​
Reverse​	4.866​	10.46​	9.97​	10.72​

 

[NotBudule2]

Speed versus RPM Calculator

OK, Sport Mode in what gear??

MPH by gear
		My Summers	OEM 18"	32.7"
RPM: 2000​	Gear Ratio	275x55R20​	265/60R18​	285/70R17​
First​	4.696​	10.84​	10.33​	11.11​
Second​	2.985​	17.05​	16.25​	17.47​
Third​	2.146​	23.71​	22.60​	24.31​
Fourth​	1.769​	28.77​	27.41​	29.49​
Fifth​	1.520​	33.48​	31.90​	34.32​
Sixth​	1.275​	39.91​	38.03​	40.91​
Seventh​	1.010​	50.38​	48.01​	51.65​
Eighth​	0.854​	59.59​	56.78​	61.08​
Ninth​	0.689​	73.85​	70.38​	75.71​
Tenth​	0.636​	80.01​	76.25​	82.02​
Reverse​	4.866​	10.46​	9.97​	10.72​

I didn't look at what gear , but i will , thanks for the chart !

 

[Dereku]

If you dont adjust your speedometer everything stays the same. Just have fun explaining that to the state police.

 

[OCL]

If you have a standard FX4, you can get away with one size up in tire size.
FX4=255/65/17
Tremor=265/70/17

The tire diameters are different. Tremor tires 1.5" taller. So your speedometer will be off. You have to use Forescan to recalibrate your speedo to the correct tire diameter so your transmission's shifting is correct. The Tremor tire size is the biggest you can go without interference with your front crash bars/rubbing.

The tire size difference seems small but it makes a huge difference in looks especially if you get wider wheels/wheel spacers.

You cannot put 33's without 2.5+ inch lift and front crash bar modifications.

 

[Dereku]

The stock tires and speedo are slightly off verses gps from the factory. You might be able to upsize 1 size with no changes. Typical of most American manufacturers. Makes mpgs look better and shortens warranty by the maximum allowed variance in speedo accuracy by law.

 

[NotBudule2]

Im aware of the speedometer issues and such , my question is , what will my new 40 MPH crusing RPM's be after upsizeing. My current RPM's are 2500 and I would be happy er if they dropped to around 2000...

 

[Superspirit]

I have 33's on mine. If you tell me what gear you are in at 40mph to get 2500, I'll go drive mine at 40 in the same gear and record the rpm for you. Have to know the gear.

 

[Dereku]

Im aware of the speedometer issues and such , my question is , what will my new 40 MPH crusing RPM's be after upsizeing. My current RPM's are 2500 and I would be happy er if they dropped to around 2000...

Thats a lot of tire. I had 46s was back went. It was like a super over drive.

 

[NotBudule2]

I have 33's on mine. If you tell me what gear you are in at 40mph to get 2500, I'll go drive mine at 40 in the same gear and record the rpm for you. Have to know the gear.

Mine likes 5th to be at 2500 at 40 in Sport Mode

I think in Tow it drops to about 1600 and hits 7th gear

Drive is horribly low rpms and I never use it...

 

[Superspirit]

I have an unleashed tune so I just leave it Drive. I Will put it in sport and lock it in 5th tomorrow and record the rpms for you.

 

[Superspirit]

Sport mode locked in 5th with 33's I got right at 2300 maybe a few rpm over. But I will tell you fuel mileage went down with the heavier tires.

 

[NotBudule2]

Sport mode locked in 5th with 33's I got right at 2300 maybe a few rpm over. But I will tell you fuel mileage went down with the heavier tires.

So only a couple hundred lower, nothing dramatic, that's good ... im aware the mpg's will suffer, but gas is pretty cheap nowadays, so no biggie there , Im still buying premium just to burn brush and wash out stain brushes and such, its a good cheap weed killer too, I keep a gallon or so in the sprayer at all times...

 

[Superspirit]

So only a couple hundred lower, nothing dramatic, that's good ... im aware the mpg's will suffer, but gas is pretty cheap nowadays, so no biggie there , Im still buying premium just to burn brush and wash out stain brushes and such, its a good cheap weed killer too, I keep a gallon or so in the sprayer at all times...

Don't know where you are, but I'll never refer to $5 gal gas cheap. I remember $0.22 gallon.
I can remember riding my mini bike to the local fuel station and getting a full tank of gas and a pack of cigarettes for $.50

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