Possible gear change in new to me Ranger

[JRMichler]

I have Nokian Hakkapellitas on my truck. They are stamped Ultra Low Rolling Resistance on the sidewalls.

[hat_man]

Just looking through Tire Rack for LRR tires. If you search for LRR truck tires many come up (even some in your size), but when you start clicking on the specs and sizes, you find that the tire has LRR sizes, just not YOUR SIZE. I could only find one tire in my size, or anything close enough to not throw off the speedo by more than 5%.

General Grabber HTS. 30 Lbs, 44 psi max pressure, and interestingly it says they have a 9" section width. (Maybe CapriRacer is on to something.) The have fairly good weather ratings. Not quite as good as my other choices, but if the LRR is that big a benefit, then this becomes my best option.

The other two choices I am considering are........

Firestone Destination A/T 205/75/15 24 Lbs, 44 psi max pressure, 6.3" section width.

Kumho Crugen HT 51 225/70/15 27 Lbs, 51 psi max pressure, 7.1" section width.

Both of the other choices have excellent ratings in weather and comfort and tread wear. The Grabbers don't rank quite as high but aren't down very far.

If you had to make the choice.........which would you go with?


Thanks

[hayden55]

What are you looking for? What size tire do you currently have? The reason why that is your ranger weighs about as much as a 4 door civic. I dont think you need ultra high load ratings either since your payload cap is nothing too.

[hat_man]

Resurrecting an old thread......

I'm still contemplating the rear gear swap. After doing some more digging I have found another option. Every rear gear chart I have seen for the Ranger only shows a 3.27 in an 8.8" rear end. I didn't want to tackle that swap and wanted something more direct.

I found this parts site and it showed a 3.27 in a 7.5" rear end. I didn't even know they existed. I know it's for a '95 and mine is an '03 but I would think they should be interchangeable.

Car-Part.com - Used Auto Parts Market

Does anyone have any more information on these and can someone please help me with the math on rpm's with this ratio running in 5th gear (0.79 IIRC) at about 65 mph? Or if you can give me the math formula I can work it out.

Thanks.

[California98Civic]

Lots of good responses. Do the 3.45... it's maybe an 8% reduction in RPMs at speed. Also, what size rims/tires are you runnig and how heavy are they? Taller and if possible lighter tire/rim combos will also bring down RPMs on the freeway without a rotational mass hit.

[hat_man]

I'm running Hankook Kinergy PT's in 235/75/15. Stock size is 225/70/15 so they are about 5% oversized. They are also LRR. 28 lbs each on stock Ranger 8-hole steel rims. I have another set of nicer looking rims but they are heavier. I figured I could try some smooth DIY wheel covers with the steelies, but aesthetically the heavier ones are nicer.

Right now I'm at about 2500 rpm at 65 mph in 5th gear. I'd love to get closer to 2100-2200, but I think the gearing to get there might be too tall for stop and go driving on the weekends. I do have a manual transmission so I can probably just use one lower gear in town.

[slowmover]

Why a pickup at all? Past forty or more years there’s a whole subset out there that believes these trucklets are useful. Crash statistics are abominable, there’s not anything worse. The whiners.

100+ miles per day commute calls for something better. Hell, a Crown Vic would have lasted longer than 300k yet still seen 25+ (and better). Excuses about convenience don’t cut it when safety akways trumps FE, and FE itself trumps perceived “usefulness” (as trailer spec would be what matters).

.

[JRMichler]

Originally Posted by hat_man

I found this parts site and it showed a 3.27 in a 7.5" rear end.

Does anyone have any more information on these and can someone please help me with the math on rpm's with this ratio running in 5th gear (0.79 IIRC) at about 65 mph? Or if you can give me the math formula I can work it out.

Start with the revolutions per mile of your tires. Then multiply by the rear end ratio, and multiply again by the 5th gear ratio. The result is RPM at 60 MPH.

Example: Assume your tires are 700 revolutions per mile (that's a random number I pulled out of a dark place). Then you would get 700 X 3.27 X 0.79 = 1808 RPM at 60 MPH.

To get RPM at 65 MPH, scale by ratio of speeds: 1808 X 65 / 60 = 1959 RPM.

[hat_man]

Thanks JRMichler. Ill get out the fancy ciphering tools and get to work.

While I do not agree at all with you slowmover, I'll take it under advisement.

[hat_man]

Ok. So after some math homework I come up with this......

3.27 rear end = 2016 rpm / 65 mph

3.45 rear end = 2127 rpm / 65 mph

Now, if I only had a BSFC for my little Ranger I could decide if the 3.27 is pulling me out of the optimal fuel range.

Thanks again for teaching me something new.