It seems my 245 50r 16's burn more gas????!!!!!!!!!

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86 IROC,canary yellow(originally black),fully loaded.305TPI WITH 700R4/SHIFT KIT,3:73 POSI REAR,4 WHEEL DISC BRAKES,T-TOPS,POWER LOCKS,POWER WINDOWS,TILT,CRUISE,SADDLE INTERIOR,POWER ANTENNAE,SPOILER OFF 87 IROC SO NO THIRD BRAKE LIGHT ON ROOF,16" BY 8" RIMS OFF 89 IROC,3"INCH EXHAUST WITH A 2 CHAMBER FLOWMASTER AND 3 1/2" BY 18" LONG CHROME TIPS,20% TINT ON SIDES,HATCH AND T-TOPS,GTS TAILLIGHT COVERS,AFTERMARKET FOG LIGHTS,PIONEER 180 WATT CD RECIEVER AND DETACHABLE FACEPLATE,WITH JENSON SPEAKERS ALL AROUND,TALKING RADAR DETECTOR"BACON ALERT"

....Long live the EIGHTIES!!!and my love for the IROCZ

 

Than what?

That is the stock tire size for your car

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"So many Mustangs, so little time..."
ICON Motorsports

 

Larger diameter tires may give you better milage. Wider tires will give you worse (more friction due to wider surface area).

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

When I got my '84, it had big 275-65-R15 (i think) tires on the 15" rims in back. I drove it up to NY from FL getting about 25 mpg the whole way on the Interstates. Unfortunately the tires were a little TOO big and scraped the fenders when I took a tight turn. They were also too wide and the car slid all over the place when it shifted, damn near killed me once in the rain.
When I replaced them with 225-60-R15's all around, it got between 20-23mpg highway. A small compromise for proper traction, IMHO.

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DR Stevens
1984 Trans Am 305HO L69
sucks gas, hauls ***
1991 Firebird 305 LO3
for days when I need a/c

 

HAHAHAHHAAAAA I bought mine that way too! They were like S5000 or something. Those things sucked! I did more then a few 180s on the turns and ramps...



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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

lol i got both you beat - i got crappy 235-60R14's and I did a 180 out at the street races when the cops showed up. I tried to run away, but for some reason the sprinklers were on at 3:30 AM. I thought Iwas goin to jail... :P

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1983 Firebird
TH700R4 Auto
Small Block 400
LG4 ECM, Intake, Carb, Distributor, etc.
Soon to be non-computer.
Clarion Head Unit 45X4
2 Pioneer 400W 12" Subs
Third Gen Performance
"A four cylinder is half an engine."

 

hahah i know the feeling man, when i take a turn and the car shifts into second......oh man im in for it if its wet out. then only good thing about drivng my car in the rain is that the shifts feel nice and smooth cause the tires just automatically spin and dont have the traction to grip and jerk the car( i have 235/60/14's)

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1983 CHEVROLET CAMARO with a 1986
305 C.I.D.V8 BORED .030 OVER
HIGH VOLUME OIL PUMP
FLAT-TOP PISTONS
MILD CAM
EQUAL-LENGTH HEADERS
3" CAT BACK EXHAUST W/ FLOWMASTER MUFFFLER
KEYSTONE CLASSIC WHEELS.
TH350 TRANNY
B&M RATCHET SHIFTER
STAGE THREE SHIFT KIT
(she'll spin em into third)

"Wise man once say, friends dont let friends drive Fords!!"

 

BioChem do you have the math for that? Physics says surface area doesn't play a part in friction. I argued in class for 1/2 an hour about this, and eventually lost. I think traction is increased by more surface area, but the resistive force should be the same. Difference between traction/friction got me. If I could find some nice proof that surface area played a part in friction, I would love to go throw it in my old physics profs face j/k Tom if you read this



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Corry Lazarowitz
clazarow@voicenet.com
clazarowitz@hotmail.com
SLP 1 3/4" headers, 3" cat back (stock cat )MSD ignition. MSD Blaster SS coil. More soon when funds are avail...

 

When it comes to math... I was adopted! My sister teaches it at Princeton, Father was an EE and did taxes on the side, mother has a math degree... I cannot balence my checkbook !

I would think that bigger tires would offer better traction at the cost of increased friction. Basically it IS the friction that is creating the traction. Also, a larger diameter tire will place more "patch" on the road.

As for why big tires suck in the rain... imagine it like a surf board. A wide area that isn't very effective at removing water from underneath it... hydroplanes nicely. Couple that with a lot of torque and you go for a ride!

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

Just take a look at the aqua-treads for proof. They actually separated the tires into two thinner tires and channel the water into that groove. Good for the rain, crappy on snow.

Chris

 

The problem with arguing the physics of tires is that most physics professors only know what the textbooks say, and textbooks cover static friction and dynamic friction. Object at rest = static friction, object sliding = dynamic friction. Unfortunately, for rubber tires there really is a whole different sort of friction called rolling friction (for obvious reasons). The additional variables for rolling resistance include tire durometer rating (stiffness), ground contact pressure (lbs/in^2), asphalt surface smoothness, temperature, and humidity. The most troublesome part of the analysis of tire friction regards the fact that the hard asphalt particles will slightly embed themselves into the soft tire compound, which totally ruins the standard physics assumption that all forces are normal to the stationary surface.

Also, with tires there is an energy transfer function which is taking place between the tires and the pavement, and a given tire patch can only transfer a certain amount of energy through to the pavement before it begins to slip.

Basically, the standard elementary physics equations don't cover tires.

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89 IROC with lots o' stuff

-=ICON Motorsports=-

 

The stock tires on mine are 215 65 R15's


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89 RS Camaro, LO3 305 TBI
L69 Duel Snorkel Intake
Dynomax Ultra Flo Cat Back

 

I run Nitto 275/40 R17s now and have no... well very few traction issues anymore


Dale pretty much nailed it too...

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

but.....

what about in the snow? wider tires don't press out the snow.. because there's more surface area for the weight which is needed to crush the snow out from under the tire and in the rain (same problem in a sense)

Now I know aquatreads are good, but a narrower tire of the same design would perform better on a lighter car (to a point as 2" tires wouldn't be too good)

And tire contact width should be within 1" of rim width or this could cause some nasty wibbly-wobbly's as some of you guys know.

All I could say is 225/60/15 and 245/50/16 are 2 different animals. One has great dry traction (16"), but man is it some scary stuff on puddled roads at fairly mild speeds, while the 15" are great in snow and rain, but suck for putting power to. (same brand and style). I'm definatly with you on the Nittos for all around dry traction. I run only 255 50 R16's and hook real hard, but only if the roads are 'nice' and the temp isn't too cold.

Imagine 15x15's in a blizzard. I'm glad spring is here


[This message has been edited by JoelOl75 (edited April 13, 2001).]

 

Hey, what's everyone laughing at? I put P275/60r15's on the back of my car (15x8) rims! I haven't wiped out once with 'em, but I drive like a snail in rain/snow/etc.


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

Yeah, the whole friction taught by professors thing has been bothering me for years. As far as anybody listening to them knows, friction is only a factor of coefficient of friction and normal force. Surface area plays no part. We all know that that is not entirely true however, why else would fat tires be good for traction? Never could get a good explaination. Maybe its time to do some research on my own. Rolling friction sounds familiar, but not from class. I'll have to check that out.