[68 firebird]

hi im new here and have a question about how to measure for new tires . i have a 68 firebird 350 i have 14 inch wheels and tires on it now but im putting 15s on it soon .how would i go about measuring for new tires? im looking for an agressive look .wide in back and alittle narrower in front. i will be using pontiac rally wheels.im not sure if it matters bu i have 2 inch drop spindals in front with disk brakes and drums in rear..any help you can offer would be great thank you verry much.

[LATECH]

If you run 14 inch rally 2 on the front you need to check that the wheel fits and clears the calipers. Some of the early rally2 14 wont fit around the calipers. Somewhere around 1970 the 14s were made to fit the small rotor disc setup. Wheels have codes and you can check that out to find the correct ones.
I would think a 195-60-14 for the front or 195 -50-15
a 255-60-15 for the rear could look pretty boss.
Go to the Tire Rack website and look into the "Tech" section. It will have articles on tire dimesions and size .You can get a good idea of the meaning of the numbers.
From there you can come up with your own numbers and tire brand tread design etc. Good luck

[68 firebird]

thanks for your help im going to be running 15inch wheels on all 4 corners so i shouldnt have to worry about the wheels fitting with the disk brakes. i will definatly check out tire rack for the dimentions thanks again

[sedanbob]

Here's a link that will also help you with wheel and tire sizes, and will let you compare to what you have now making it easier to measure. Custom rims, wheel tire packages for your ride - RIMSnTIRES.com

[vinniekq2]

You did noy say if you want factory wheels or after market wheels?The factory 15x8s fit the back and some 15x8s fit the front.My 67 Camaro used 15x8 and 15x7 Corvette rally wheels.Ive used 15x10 on the rear with 235x60x15s,Ive used 15x4 on the front when racing,,,horrible street manners with skinnys up front. For after market wheels you can measure clearances and have custom offset wheels ordered.Go conservative with back spacing.
REMEMBER: the car was designed to have a certain size wheel/tire,straying too far causes other issues.For full explanation look up S.A.I.
steering axis inclination,get someone with road race experience to explain to you what happens when tire height is greatly changed,then get a custom wheel alignment quote

[vinniekq2]

PS: re 68 firebird..
the frame horns are known to spread with age,check to see how many alignment shims you have in both sides of the car now. Get the frame measured and consider subframe connectors and bending if required

[lakeroadster]

Originally Posted by 68 firebird

.... i will be using pontiac rally wheels.....

1968 Firebird eh? Nice!

Since you have already chosen the wheels you will be using I'd jack up the car, remove the exisiting tires and wheels from one side and then set the car down using jackstands under the suspension. Then bolt on the bare Pontiac rally wheels. You should now be able the measure how much space you have for tires.

The problem with using the Tire Rack website is you're dealing with a vehicle that is 45 years old. Unless it's bone stock chances are components have been replaced. Your best bet is to measure what you have. In the rear the shocks will likely limit the tire width. If needed you can trim the fender lip for some additional clearance, or roll the fender lip under.

I have a stock '69 Camaro and there is a lot less space than you would think for rear rubber, unless you make some modifications. In my case the car is so nice I didn't want to cut or alter it. I ended up using the following:

(4) American Racing#286-309-5761 Torq-Thrust TTO Series 309 Wheel

Size: 15'' x 7''
Bolt Circle: 5 x 4-3/4''
Rear Spacing: 3-3/4''

(2) BFG Radial T/A 255/70SR15
(2) BFG Radial T/A 215/60SR15

Hope that helps.. good luck to ya and post up some photo's of your car.

[sedanbob]

Originally Posted by vinniekq2

...REMEMBER: the car was designed to have a certain size wheel/tire,straying too far causes other issues.For full explanation look up S.A.I.
steering axis inclination,get someone with road race experience to explain to you what happens when tire height is greatly changed,then get a custom wheel alignment quote

Excellent reminder! I set up my alignment following what several sources suggested and it was 'skitish' at speed. Always felt like it was on the edge of out of control. I found a real alignment shop (not a tire store with computer alignment setup). It was not cheap, and took several hours. The result is a very stable ride and excellent handling. Changes in ride height, wheel/tire size, chassis rake, all factor into getting that alignment right.

[vinniekq2]

lakeroadster
Nice 69,350 or 396?
My 67 had the bumblebee stripe. They are and will always be icons,67/68&69s

[lakeroadster]

Vinnie,

350, 3-speed Muncie. It has lived here in Colorado it's entire life, and the dry climate has been kind to it.

[vinniekq2]

lakeroadster
thats a beautiful car
I would still have my 67 if it wasnt stolen,,,,
I will always be close to those cars,guard yours with w/e it takes to keep it safe

[lakeroadster]

Thanks Vinnie, good advice. Got any old photo's of your '67 you could post up?

[cadillacdave1]

I also have a 68 Bird. I have replaced the rear leaf springs with heavy duty leafs (5 leafs) which raised the car up from the old factory leafs, which were worn out. I run a 295/50/15 BFG radial T/A in the rear and a 235/60/14 in the front. I have seen other folks runs a 275/60/15 in the rear with no clearance issues.

[vinniekq2]

Originally Posted by lakeroadster

Thanks Vinnie, good advice. Got any old photo's of your '67 you could post up?

I will scratch up some pics if I can.

[68 firebird]

hi everybody thanks for your comments and advise. thats a gorgous camaro Lakeroadster your combo looks good.i would like to go just alittle wider in rear though..rite now i have an old set of pro track 50s they measure 10 inches wide but they are real short i want to fill my wells up thats why im going to 15 inch.not to meantion cant find that wide a tire in 14.i was thinking 70s in front