Boat tail on a normal car? (3-box sedan)

[orange4boy]

You could go a bit steeper and still end up with the 10-12 degrees that gives the lowest drag although what you have there is good as is.

[Pendragon]

Originally Posted by orange4boy

Nice progress on the tail. Subscribed!



Just had to correct you here. All the studies I have seen do not back this statement up. LRR tires have to be taken on a case by case basis. In a recent tire test in Europe many of the LRR tires tested had higher traction numbers than the HRR tires. In fact the two top tires were LRR. The Nokian H came out first in the test followed closely by the Michelin Energy saver. This was in a group of premium tires of which 4 out of 9 were LRR. Nokian also sells a LRR snow tire, the Hakka R which is one of the best winter tires out there. On the other hand, the famously ultra LRR Bridgestone B381 for the insight is a pretty mediocre tire in the traction dept. The carcass has a lot to do with LRR which does not factor into traction much. It's all about quality

Actually, it is much more complex than that. "Quality" is not the main issue. The compromises made in the design and construction of the tire are quite involved and the technology is still "emerging". Specifically, compounds used in the tread have a great influence on rolling resistance, braking, and traction. There have been indications that some of the LRR tires in Europe have failed tests for braking and have caused the EU to reevaluate their proposed standards requiring LRR tires.

It is true that each tire must be evaluated on its own, but as a class LRR tires should be approached with caution. There is also the matter of just what a LRR tire is. The marketing people at the tire companies are as adept at "spinning" as anyone else. There are "energy", "green" and other terms that have no particular meaning and (unsubstantiated) claims without outside testing to determine their validity. The consumer does not have the ability to do this sort of thing. Some web sites, such as TireRack have a certain amount of testing, but even they are challenged to comprehensively evaluate LRR tires.

In any event, the evaluation of tire performance is not easily done and each individual must consider which characteristics are most important in the driving conditions which they expect to encounter most often.

It is not appropriate to simply say "get some LRR resistance tires".

Cheers

[euromodder]

Originally Posted by Pendragon

There have been indications that some of the LRR tires in Europe have failed tests for braking and have caused the EU to reevaluate their proposed standards requiring LRR tires.

That's what happens when too much emphasis is placed on the LRR factor.
Tyres are, and highly likely always will be a compromise.
You can't win, you're only trading off for something else.

The problem is there are no challenging minimums for braking and handling.
So we can still get badly handling tyres with great LRR and FE, while first and foremost you'd want a tyre that handles and brakes decently, but still has good RR.

The Michelin Energy Saver is about as far as I'm willing to go in this trade off.

[NachtRitter]

Originally Posted by Pendragon

...

It is not appropriate to simply say "get some LRR resistance tires".

I would say that's true regardless of which type of tire a person is looking for... "performance", "mud & snow", etc. Just because the manufacturer claims the tire has a particular characteristic, does not mean it compares well to others in its class. Nor does it mean it meets all the specs you might want. Even the same tire in different sizes, or spec'd for a certain car, can have different behaviors. It is complex, so buyer beware, YMMV, etc.

[orange4boy]

LRR tires meet the same federal standards for treadwear, traction, and temperature resistance as regular tires.

Originally Posted by Pendragon

all low rolling resistance tires have made compromises which have made the tire's performance in braking and wet weather traction less than many of the tires which are not marketed as low rolling resistance.

That's the statement I'm addressing. That's an over generalization which gives the impression that all LRR tires are crap. If you had put 'some' in there I'd be cool with it.

I absolutely agree with you that tire purchases require some thought and study to wade through the hype. Sadly very few people bother.

As for the "Energy Saver":

From Autoblog Green:

According to Consumer Reports, both the Michelin Energy Saver A/S and Cooper GFE served as good all-purpose tires, but the Michelin Man came out swinging with superior performance in rolling resistance along with wet and dry braking. In fact, so good was the performance of the Energy Savers that they would slot in at number two on CR's chart of all comparable tires regardless of their rolling resistance rating.

Sorry about the thread jacking... Back to the tail...

[Pendragon]

Originally Posted by orange4boy

LRR tires meet the same federal standards for treadwear, traction, and temperature resistance as regular tires.

Not to make too fine a point of it, but there is not a Federal "Standard". There are rating or classifications: A, B, C etc and the tread wear ratings: 240, 320, 600 (gee, I wonder just how those tires feel in the rain).

The point, which I think you agree with, is that it is not easy for the average consumer to make an informed choice. If they are lucky, the tire store will have someone with some experience to assist them.

Cheers

[cliffyballs]

So for right now im thinking i will screw the fittings to the car then drape fiberglass cloth over the pvc and on to the body of the car, then fiberglass it to the car. That is what im thinking any suggestions?

[orange4boy]

I would highly recommend making it removeable. You could rivet tabs on to the car then bolt the tail on to the tabs. Tabs could be made from some aluminum T bar.

[Weather Spotter]

I second the removable idea you will want to take it off at some point so plan for it now

[NachtRitter]

Ya, I'd 3rd the idea of making it removable...