Revamping/Improving a tech article: Tire/Gear chart

[Brain75]

I figured my truck was turnin' out too high an RPM for any chance at a decent MPG goin' 75mph down the road, so turned to the calculators and charts here on TRS only to find they were a little lacking... I whipped up a quick XL spreadsheet and then said, why not share it back to the community... so here is a discussion, request for more info, additions, and feedback opportunity to improve it before I tie up even more of Jim's time...
this chart:

Gear Ratio & RPM Guide For Larger Tires - The Ranger Station

This Gear Ratio & RPM Guide will enable you to see how many RPM's your engine will turn based on gear ratio and tire size.

www.therangerstation.com

has some gear ratios that as best I can tell are irrelevant to us, and some tire sizes past the far end of what a guy could squeek under a ranger, along with some missing data and the fact it is static hard locked to 65mph, and a final drive ratio of 1:1 (no overdrive).

So my XL spreadsheet addressed those and after a couple hours or polishing off some rusty javascript I have a working copy that is dynamic on both the final speed and final drive ratio.
I can't post the HTML here in a working format (thankfully for safety measures to protect Jim/the site), so here is a screenshot.

My questions to the community:
A) missing info - anyone know the ring and pinion teeth count for sure of the 2.73 and 3.31 rear diff gearsets? (I put in my best SWAG - Scientific Wild Ass Guess)
B) does anyone make gear sets further out on the extremes than 2.73 or 5.13 AND do you want them in the chart?
(if so I am gonna need teeth counts)
C) I dropped some ratios that don't look to exist in 7.5"/8.8" or 9" - are any of those ratios needed to be put back? (if so what are they off of so I can add them and info)
D) really common tire sizes, I kinda knew the most common 1st gen / 2nd gen / 5th gen sizes but not so much on 3rd, etc - care to share those and I will add them.
(I know if you got a splash or stx or tow package they got different sizes so "stock" OEM is 200 different sizes, only looking for the 90% most common, 1 per generation)
Also if anyone can argue that 90% of the rock crawler crowd all look at XYZ size that is not on the chart and it is super common - share that size and I will add.


The light blue MPH and Final (OD) Ratio are user modifiable so you can play with swapping trans out to see the differences between Trans A and B.
The pink tire sizes are also user modifiable so you can plug in a tire size I didn't put in.

I "think" everything else is self explanatory, but now is the time to ask so if it isn't clear I can type up a little whatzit/how-to-do.

 

[JoshT]

On your security point, can you make the spreadsheet without using Javascript? I would think that basic Excel spreadsheet formulas should be able to cover the functions.

I like what you're thinking, but honestly I think you're putting in a bit too much info, making it too busy. Not putting down the work you've done at all, but here are a few thoughts and ideas.


You don't need to provide axle codes. There are a lot of available axle codes especially once you move beyond the Ranger and Explorer axles. Remember some people like putting full width axles under these small rigs. The codes are readily available elsewhere in the tech library and online. Having the available gear ratios is enough IMO, though the tooth count is an interesting tidbit of info. Possibly add a column for user input gear ratio like you did for the tire size, for those people who may not be running Ranger axles.

Instead of providing MM, IN, and OEM/popular sizes (there are a lot), I think I'd just do inch since that is what most people using this forum are familiar with and convert to when talking tire size. Seems to me the MM would get confusing to the uninitiated because metric tires aren't measured in diameter. You have no idea how many times I've asked what size tires are you running and gotten back something like "235" or "265" like that's a complete answer. I usually just nod my head and carry on knowing it isn't worth the effort.

Instead of MM and OEM tire sizes, maybe add a calculator/converter for metric sizes to inch diameter. They could then match that up to the closest inch on the chart or input into the user parameter box.

Tire diameter = (section height)/25.4 {to convert to inches} x 2 + (wheel diameter)

Section Height = (aspect ratio) x (tire width)

245/45R17 = ((245 x 0.45)/25.4)x2 + 17 = 25.7

Hopefully I typed that out right. Sorry if I'm giving you info you already knew.



If I can find it sometime, I had once saved another spread sheet that could be useful like this. It provided RPM and MPH for each transmission gear for a given rear axle ratio and tire size. Was not my creation, something I found when parusing a British car forum. Was rather interesting.

 

[alwaysFlOoReD]

There is a metric to inch conversation thingy in the tech section (or somewhere on site), I've used it numerous times. Maybe it can be Incorporated?
I like the axle codes there, especially since they are there already.
I agree the mm diameter isn't needed.

 

[2011Supercab]

https://www.blocklayer.com/rpm-gear

 

[Brain75]

It started out as a XL spreadsheet and I could share a google drive link to a spreadsheet, but Jim isn't hosting 100 links to google drive, figured put it into a format that directly can be published by Jim and then he owns it - I have no problem relinquishing control after I hand it off to Jim.

Mostly all info that I already knew and one of the reasons why I did mm and ring/tooth counts is accuracy. Most of the charts I have seen people shorten the 336.13 in the formula down to 336 (easy to remember I get it), but then round down your tire size and round down your axle ratio (to just 3.73 instead of 3.7273..... etc - yes the formula uses the math not the rounded) and suddenly you are off not just by a rpm or two or even 50 but all that rounding compounds and you are off by 100 rpm.
Before I even saw Josh's response I added the user entered diff ratio column, but thanks for justifying my itch and midnight work... At first I decided I was going to be lazy and not bother since in the very corner you end up with custom code on top of custom code to deal with the user entered both rows/columns, but looked at it cross eyed for a minute and decided how hard it might be and just wrote it - so here it is:

Fwiw, I included the door tags so I can print off 1 page and take 1 sheet of paper with me to the junkyard during axle hunting instead of 4 separate charts from 3 different pages of the tech library... info is not "all together in one place" as it is now and a little irritating (to just me at least).
I did't show working examples since it is a static JPG, but it self calculates- so if you put in 33.5 (say you actually find english LT 33 1/2 tires) when you enter that in the pink cell for inches it will automatically populate the cell immediately to the left of it with the metric (the formula from a million hot rod sites is built for inches so even if you pick metric it converts it to inch to stick inch values into the formula).

I could have easily parsed "265 / 60 R 16" and done the math under the covers but I was too lazy to write all that code when it exists in 200 other places... someone can either re-code my work or go to a calculator to find out the end number to put in the chart.

As it is now I have preloaded (user changeable) values of 0 for the 3 user entered pink cells and 75 for the mph and 0.79 for final drive ratio.
I calculates OnLoad, and on button press I was thinking of spending a minute to look up the code for input box change but again that is looking stuff up I don't know offhand.

And the whole thing is re-sizable without too much distortion, so maybe might even look ok on a cell phone - don't know.

(the two different almost identical screenshots are different sizes and user entered values plugged into the pink input boxes)

@Jim Oaks If there is nothing further give me a place to send the HTML and I will ship it to you to check and use (I figured out how to post it in the test forum, but it isn't processed, it is just syntax highlighted plain text.. that works if that is the easiest.)

 

[Brain75]

https://www.blocklayer.com/rpm-gear

where were you at when I was shopping for the 9" to go under my '48 (right after I switched to the T5 tranny)... this would have been a lifesaver and probably made me pass on the axle I got for a better choice.

Jim, you need to swipe this site too

 

[Brain75]

The more I think about it the more I have to agree the user entered mm probably would never be used... On one hand I coded it and would rather leave it in case someone would use it... and I swear discount tire used to list their "specs" on tires with the mm (which is more accurate to a couple more decimals than inches.tenth, no hundredths... but at the same time a brand new tire with 10/32" tread and a bald cueball with 0/32 left have 20/32 difference in overall diameter more than a half an inch.... at some point you quit chasing the decimal place and say "this is close enough".

I don't see 1010tires as having mm specs either, it's simple to delete it, just rather not and get asked to put it back.

 

[Jim Oaks]

@Brain75 email the html file to me. Jim@ you know the rest.

We have a metric tire size converter calculator at:

Tire Size Calculator & Size Chart - The Ranger Station

 

[Brain75]

any changes you would like?

 

[Brain75]

Ok so this is my last post I promise.... (I'm hitting send on the email now)
I sat back and asked why did I want all the 1st/2nd/etc generation stock sizes and for 'me myself and I' the answer was "so I can compare what I have (215/70R14) to xyz I am considering" well if I take all those out the info wont be there anymore, and people are back to going with the "next closest size"... The solution - 2 metric entry boxes (and for those wanting to compare 1/2 inch english sizes or know offhand the exact inch size of some metric, 2 inch entry boxes)... simplify the code to eliminate some fancy wizardry by doing simpler wizardry much earlier and voila.
A guy has all the typical inch sizes, can enter 2 different metric sizes (I did the coding work I said I was too lazy to do).... and so on and so on.

I looked into the refresh on entry instead of a button and it would make the page run slowly and chew up CPU...
Think about typing in 235 75 16... and the computer does 2 (recalculate) 3 (recalculate) 5 (recalculate) , etc etc... runs like

sample date makes it easier for a user to grasp what the heck they are supposed to do, so I made the default diff a common 9" ratio, and a couple of the tires etc etc - you get it - no defaults of zero.

 

[Jim Oaks]

I can't add that html to the pages on the main part of the site because of all the java script.

I had to add it here:

therangerstation.com/how-to_pages/rpm_calculator.shtml

Any of the pages I add to this are uses a header:

therangerstation.com/how-to_pages/how-to_header.htm

As you can see here:

Gear Ratio Guide For Larger Tires

I save all of those pages as shtml instead of htm which allows me to add this code just after the </head>

<!--#include file="how-to_header.htm" -->

That loads the header page at the top of the page.

I haven't been able to add a header onto your page.