My 86 Jetta TD

[nathantheengineer]

Does 55 psi cause the tyres to wear in the centre?  i have always set my tyres to 30 psi. 

I do approximately 1000 miles per week so an increase in mpg would be desirable but only if i maintained my journey speeds/times.

Tyre wear would be a contentious issue too, would i gain enough increase in mpg to offset the handling issues and the tyre wear?

The last 30 miles of my commute are across the moors so handling is important to me.

Kind regards

Nathan   

[scrounger]

That is a great question. Stiffer  tires mean less comfort. but less flex and more responsive to a point. More tire pressure means a smaller contact patch but more pounds of car per  square inch. High pressure can cause the tires to bulge unexpectedly and fail if too high.  The tires are stamped with a pressure that the manufacturer has suggested as the maximum that it has been tested to run at.

That said I went up on pressure gradually, I too was skeptical.  Been running these kind of pressures on all my cars and trucks for the past 3 years. As far as wear patterns go, I notice that I am not wearing the front tires out on the outside edges like I used to. I always blamed aggressive cornering, ei: tending to roll the front tires off the rims while cornering. I have always been easy on brakes but hard on tires.  Having wider tires than recommended on stock rims probably will wear them on the middle if the pressures are too high.

I run winter tires all year round. They are not deep lug but more aggressive tread than regular road tires.  They are not slippery at all and great in the rain and snow. I am not worried about dry weather traction as it is abundant. Problems with traction are mainly when the weather is bad.

Will my car hang with a similar car with low profile high traction tires in the dry, say on a skid pad? I would say not.  But on a oil slick or snow covered road my vehicle probably will have lost a lot less and won't be in the ditch.

[nathantheengineer]

Thanks for the swift answer, i too am hard on tyres and less so on the brakes.

The outer edges of the TD tyres are wearing but the previous mk3 ( a vr6) did not wear the outer edges of the tyres at 30 psi.

I assumed that i was rolling the tyres off the rims whilst cornering. My reasoning was that i am still on the skinny 13" 4 lug steel wheels whereas the VR was on a wider set of alloy wheels with a stiffer sidewall.

My next step is to have the car fully 4 wheel laser aligned. 

I have a feeling that a couple of the suspension bushes are worn so PU replacements will be required before the alignment.

Depends how long i keep the car as i think it needs wider wheels with lower profile tyres to kerb the understeer that it is currently suffering from.

the other option i suppose is to slow down but hey ho.

[burn_your_money]

Just noticed this thread. Pure Awesome.

I'd do this if I had a car, but I think it would look pretty stupid on my F250, not to mention close to pointless. Although...

My brother build almost a full length skid plate for his Diesel Chevette. He said it made a fairly big difference in his MPGs. He didn't do it long enough to be 100% conclusive before he added WVO into the mix.

[8v-of-fury]

Tyler, you and your brother are awesome in its most elemental state. PURE-AWESOME! His Chevette is friggin awesome. Does he still rock that angle bar setup off the front bumper ?

I have been running older M/S tires since the snow went away this year. Tires that are a little harder so don't work as winters anymore but still grip that dry pavement like no other. Pretty sure they are 195/75/14's, they are wide. I have ran them at their 46psi limit since spring, still got them on there actually. They handle with a very predictable stiff handling.

[JBG3]

I have a standard MK3 golf which does 60mpg, and doesn't look embarrassing 
Surely there are ore aerodynamic cars to chose from if MPG/hypermiling is what you're aiming for?

lol, If I could jump my 86 from 47mpg to 56mpg by bolting a 6 foot tall head of Ron Pearlman to the roof, id do it, and be damned to anyone who didn't like it.  Id be laughing all the way to the bank.   

[JBG3]

I love this idea, Id love to try and make one for myself as well and see if I could get similar improvements with a 1.6 NA.  

How did you determine the best angle of the trunk fin in relation to the roof fin?  (which I see was from the airflow pic of the golf)

[8v-of-fury]

I have a standard MK3 golf which does 60mpg, and doesn't look embarrassing  
Surely there are ore aerodynamic cars to chose from if MPG/hypermiling is what you're aiming for?

Ahh, but if you convert that to US MPG instead of your IMP MPG.. You are only getting barely 50 US MPG. He has got you beat by nearly 7 whole miles per every gallon, in a much less aerodynamic car. Also, chances are your mk3 was built in Germany, and isn't rotten like every mk3 here in North America.

[snakemaster]

went a 250mile trip with a mk3 golf tdi estate  sat at 50 55 mph and 72mpg UK tho for a car of 1320kg  but with std 14" wheels, and can get 70mpg from my mk2 golf 3 door MTDI tdi gearbox to all in 850kg

[8v-of-fury]

went a 250mile trip with a mk3 golf tdi estate  sat at 50 55 mph and 72mpg UK

Is that your highway speed?

[snakemaster]

went a 250mile trip with a mk3 golf tdi estate  sat at 50 55 mph and 72mpg UK

Is that your highway speed?
[/quote
60mph and on the 2lane 70mph 
i am not in a rush so 50 55mph dose me fine 8ish$ to a poxy gallon right foot up 

[8v-of-fury]

You do 20 under the speed limit? Unfortunately, that would never fly on this side of the pond.

[snakemaster]

You do 20 under the speed limit? Unfortunately, that would never fly on this side of the pond.

i use to run my 76 dodge tradesman van 318 at 50 55mph your side of the pond all the time 24mpg with that sucker , was in no rush just picking up the sights , glamis ,little sahara dunes,coral pink sand dunes ,etc,with my quad to in the back , best days ever

[8v-of-fury]

i use to run my..

Also it depends where you were too.