Tallest 5th gear possible

[bbob203]

Absolutely.  If I had an AVX in an ECO I would most certainly swap it out along with the injection pump and the soda straw exhaust...

The eco exhaust is at least bigger than an na exhaust.

[Jetmugg]

Get taller tires.

[Gizmoman]

That's what I did on the van - works good but it raises all of 'em.
I have a K14 and getting the breadbox rolling up a hill from a dead stop is trickey.

I'm speaking from memory though - I'ts been in rebuild mode for over a year

[92EcoDiesel Jetta]

Get taller tires.

Is the results the same as changing final drive at same rpm?

[8v-of-fury]

175/70/13 with 3.94 and .71 is 2500 @ 60 - with 3.67 and .71 is 2300

185/70/14 with 3.94 and .71 is 2300 @ 60 - with 3.67 and .71 is 2100

[92EcoDiesel Jetta]

Aerodynamics aside from bigger tires provided there is no interference in wheel wells, seems much easier than changing the diff to lower rpm.

[libbydiesel]

There are more significant downsides to larger tires than aerodynamics, most notably the added rotating mass hurts fuel economy during acceleration (similar to added weight in the car) and makes the brakes less effective (similar to added weight in the car).  It's a better idea to get close with gearing and fine-tune with small changes in wheel/tire size.  When you consider the cost of used larger rims and new tires the cost is more than a good used trans.  Swapping a trans is a little more work than swapping 4 tires.  The trans you pull out can usually be sold for close to or the same as what you pay for the taller geared one - there are certainly folks who want the close ratios for added pep.  Used 13" rims and tires are hard to give away and go bad on the shelf.   

[92EcoDiesel Jetta]

If rotating mass is an issue why are new cars going with bigger and bigger wheels? Why not go the other way?

[libbydiesel]

The short answer is that cars have gotten heavier to accommodate stricter safety requirements and given two sizes of the same model of tire with the same aspect ratio, the larger size will carry a higher load rating.  Heavier cars = bigger tires.  Newer cars also have much larger brakes to accommodate stopping both the heavier car and the bigger tires...

[CrazyAndy]

The short answer is that cars have gotten heavier to accommodate stricter safety requirements and given two sizes of the same model of tire with the same aspect ratio, the larger size will carry a higher load rating.  Heavier cars = bigger tires.  Newer cars also have much larger brakes to accommodate stopping both the heavier car and the bigger tires...

Also the trans final drive is selected with both engine power, vehicle weight and wheels' tire size taken into accommodation.  That's why the 2013 passat TDI rides at 70mph @ 2250 on a relatively flat beltway-style freeway and has good power.

[8v-of-fury]

If rotating mass is an issue why are new cars going with bigger and bigger wheels? Why not go the other way?

Those bigger alloy wheels are probably still not that much heavier than our thick gauge steel rims.

I didn't notice any hit in mileage or performance when going from the 175/70/13 to the 185/65/14's on the mk2.