[diesel_john]

The tires i have on now are 175sr13 and not only heavy but square on the edges, i gained 5% mph over the 155's but no mpg gains, the cause i believe
added rotational inertia, added rolling resistance, added aero resistance,
dropped RPM's
Net gain zero. the good news is they are michelins, the bad news is they are going to last 100,00 miles
Coker sells a 135sr15 but that would mean making custom rims and fender mods.
The space saver idea was to use the space saver rims with the 135sr15's and weld in my centers, was hoping vw made a saver rim with the 4X100mm pattern.
Drag racing fronts go down to 2.5" wide and rated 200mph, but again custom rims. some are DOT rated but not many. do the front wheel drive drag racers use narrower tires on the back, if so DOT rated?

roflwaffle suggested swapping the stock 3.89 final gears for 3.65's which occured in a "6G" vw trans. 8/82-7/83. i haven't found out which vehicle that was in yet. i was hoping to swap the whole trans. And/or boring honda vx rims to fit my hubs which could net lighter rims, (mine are 15#) el cheapo 145sr13's might end up being the lowest total inertia if that trans would happen to fit the diesel, to keep the rev's down.
Which is what Big Dave has been saying all along, small tires and tall gears.
Note: the grasshopper on the hood held on up to 45MPH. no good, so I took it all back off. I had splitters on the top, bottom and middle and some one talked me into cutting them off and it just killed the mileage.