[Blackcat]

It seems like it would be cheaper since it is a maintenance item and the effect on handling would be small.

It would also fix the speedometer reading low. Both larger tires and the 5th gear swap would change the gearing and if you have an auto, your only option is larger tires anyways.

 

[Vent5]

Simply put, because taller sidewall tires affect every gear and 5th gear affects only 5th gear. Taller tires change handling more than you think. If you go wider too, it lowers economy. It increases handling too, but you might have to use a wider wheel for the best tire fit.

 

[rickb]

If the sidewalls get too tall, they squish down during cornering and this reduces cornering handling. But during acceleration and braking, the sidewalls squish and this increases the tire's footprint and increases acceleration and braking. But the larger footprint also reduces fuel economy.

 

[chittychittybangbang]

I just went from my regular tires to winter tires and wheels. The regular tires are slightly oversized compared to the winter tires. I think the diameter differernce is about .5", which is not a lot. I could feel a huge difference in clutch engagement, power delivery to the wheels, etc. My only mods are chip+mild nozzles, the PP357.

IMO, larger tires are similar to 5th gear, but 5th gear only puts the car exactly where it needs to be. Larger tires + 5th gear, at least in my case, was too much at the lower gears and too much in 5th gear.

 

[jon applespeed]

You cna feel even small differences in tire size. Plus, there is a limit to how big you can go. The tires might rub against the suspension or fuel filler port. They also affect handling in a way that 5th gear doesnt.

Bottom line: 5th gear swap can change your gearing on the highway only and is pretty well likeed by peole who try it, tires affect everything in a way that may or may not be desireable.

 

[blupearl]

I've been in a car that had the 5th gear swap. It's doesn't change gearing in 1-4 gears to the point where you feel like it's perfect in 5th. 4-5 is a bit taller but not really noticeable. It's one of those things where if you think you might want to do it, then go for it! It's also a chance to clean out the old gear oil.

 

[Silver Bullet]

Big Tires

It seems like it would be cheaper since it is a maintenance item and the effect on handling would be small.

It would also fix the speedometer reading low. Both larger tires and the 5th gear swap would change the gearing and if you have an auto, your only option is larger tires anyways.

I've done ~30K with oversize tires (205-65/15) and am very pleased with the result. It reduced my RPMs just a bit at speed and I believe gave me better mileage (not a real issue as I only fill up once a month or so). I never noticed any handling issues and the car rides better and quieter with the larger tires. Yes, my speedometer is off but I drive by providing assured safe distance between me and the vehicle in front of me. Also, while admittedly not much, they give me a bit more ground clearance....which is a good thing. I don't recall them ever rubbing.

I used to have a ~84 Jetta with three sizes too big tires on it. You could tell a difference. Not much punch.....but very quiet.

Does anyone know what the biggest size is that MK 4's will take safely?

 

[chittychittybangbang]

I used to have a ~84 Jetta with three sizes too big tires on it. You could tell a difference. Not much punch.....but very quiet.

Does anyone know what the biggest size is that MK 4's will take safely?

Way too many factors but generally speaking, +2 size will work, there is some room for increasing the width or aspect ratio of the tire.

If you have a softer suspension it will let the tires move move and rubbing is possible. TDIs have a mix-match of springs so otherwise identical will be slightly different.

wheel size and wheel offset aka. how much it sticks out in relation to the hub. If the wheel moves in then so does the tire. If the wheel moves out then so does the tire. These can place the tire close to the brake lines, suspension, or the fender. Stock VW wheels are about 35-38mm.

And different tires have different construction - some have small lips, some bulge out the sidewalls.

It's hard to say so the best thing to do is to know your current specs and compare it to what you want - here is a good calculator to measure the difference -

http://www.venommotorsports.com/library/tirewheelcalculator.asp

 

[Fluid]

Way too many factors but generally speaking, +2 size will work, there is some room for increasing the width or aspect ratio of the tire.

If you have a softer suspension it will let the tires move move and rubbing is possible. TDIs have a mix-match of springs so otherwise identical will be slightly different.

wheel size and wheel offset aka. how much it sticks out in relation to the hub. If the wheel moves in then so does the tire. If the wheel moves out then so does the tire. These can place the tire close to the brake lines, suspension, or the fender. Stock VW wheels are about 35-38mm.

And different tires have different construction - some have small lips, some bulge out the sidewalls.

It's hard to say so the best thing to do is to know your current specs and compare it to what you want - here is a good calculator to measure the difference -

http://www.venommotorsports.com/library/tirewheelcalculator.asp

Great calculator! Much better than the miata one.