Date: Fri, 13 Jun 2008 19:12:43 -0700
Reply-To: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Subject: Re: Better MPG - wheels and tires ?
In-Reply-To: <4852E6A2.1060604@charter.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
In terms of 'unsprung weight' ..............the part not held up by the
shocks and springs, ..........less is always better for HANDLING......
negligible affect on fuel mileage.
The original purpose of alloy wheels was less unsprung wieght - and so
was indpendent rear suspension..........and inboard brakes......the idea
is to make the unsprung wieght as low as possible so the springs and
shocks can make the tires follow the road over bumps better etc.
the rotating mass of the wheel/tire combo- you don't want to change that
drastically from stock either. Just makes the brakes have to work harder
etc.
having a tall tire or large diameter - that affects gearing of course.
And do not automatically assume that taller gearing always translates to
higher mpg - one subaru vanagon guy did that recently - went to about a
10 % larger diatmeter wheel/tire combo and LOSTan mpg or two at cruise
speed.
however............... LOWER ROLLING RESISTANCE is what you want for mpg.
I just the other day took off some 205/70 R 14 tires from my 85
Wolfsburg Weekender and put on 185 R14 C ........'real vanagon tires'
............the properly rated ones........
as soon as I hit 35 mph I could feel that these 'new' tires glided along
noticeably better. Like 10 % easier too , i'm sure. Fortunately
I have about 10 vanagons and a dozen sets of different tires and wheels
to try on my own personal Vanagon, so it's easy to get back-to-back
comparisons.
regarding the 185 R 14 C...............there are D rated ones of those
commonly avialable now. Too stiff for my tastes - but............a Tire
Store said to me - yeah, people use them for trailer tires.
AND.............'the thing' in a trailer tire is , load carrying ability
obviously but also low rolling resistance.
I have a two wheel utility trailer..............and I had been renting
U-haul trailers to move, and the first time I used my 'new' used
trailer, it towed really 'heavily'..........it had car tires on it. Car
tires mush out more and flex more..........and have considerable higher
rolling resistance than properly rated real vanagon tires, or trailer tires.
I also notice these tires that are rated for about 1,800 lbs each and 65
pis max cold............have very ordinary tread patterns.
As do 18 Wheeler Big Truck tires.
it could be that with a LOT of wiegh on the tire as they are built for,
they have quite good traction anyway, even though their rubber compound
and tread pattern is not optimised at all for traction and cornering.
I am quite sure there is up to 3 mpg avialable blable in the 60 to 65
mph range just from the right tires.
and it's LOW ROLLING RESISTANCE that we want for best mpg.
and wheel size has very little to do with that.
I don't think there is a rating for rolling resistance for tires, yet.
Go to tirerack.com............you can read about 20 specs for hundreds
of tires there.
Also.........you'll notice older cars came with pretty modest tires and
wheels on them.
there are advantages to those - cheaper for one thing. But also ride,
handing. and rolling resistance.
You will 'loose' in some areas for sure going to far bigger tires or wheels.
i could say a lot more, about the conflicting requirements tires have to
deal with - but I'l stop here !
scott
turbovans
ohn Rodgers wrote:
> I'm no tire expert, but it is interesting to note the kinds of tires
> that are run on the vehicles that are tun on the Bonneville Salt Flats
> during speed trials. Those suckers use huge rims with narrow tires with
> low sidewalls. Not much tire there really. I guess this contributes to
> much lower rolling resistance.
>
> I have been for a long time running a wider tire, but next tire change
> I'm goig back to the stock tire width for the Vanagon. Reason being I
> want every advantage I can get given these high fuel prices.
>
> John Rodgers
> 88 GL Driver
>
> Joel Sell wrote:
>> I am interested to see where the "under the front end aerodynamics"
>> thread goes, but I'm also wondering about wheels and tires. Short of
>> purchasing racing wheels which I think are illegal to use on the
>> street, what are our options for lightening up our wheels? Also, Is a
>> 14" wheel with a tall tire better than an 18" wheel with a low
>> profile tire? I know that thinner is better, and it seems that as
>> wheels increase in diameter, they also increase in width ,but
>> assuming you could stay thin, is a tire with a tall sidewall
>> better/worse than a tire with a low sidewall? How about overall
>> diameter?
>> August '06 Popular Mechanics says that "rotating weight of a spinning
>> tire is 1.5 times its actual mass- so this is an area where trimming
>> pounds really pays off".
>> Any thoughts on this?
>> Joel in Philly
>>
>>
>>
>
>
