Products to Compare (max of 3)
Compare These Parts

How to Convert Bias-Ply Size to Radial Tire

Add Article To List
Tags: Tech, Tech
Bias-Ply Tire Sizing Difference
Vintage Firestone Tire

That classic you’ve been restoring is just about done, but it needs new tires. Not a big problem, really. So you wipe the dust off and look for the P number that you are so used to seeing on all the current tires. Problem is, you don’t see it. What you do see, however, is a number that says 700-14. Turns out the last time your car had new tires put on it, they were bias-ply. Bias-ply tires used a slightly different sizing arrangement then the P-Metric scale used today. This article will give you a little help on figuring out what size is closest for your car.

Changing from Bias-Ply to Radial Tire

You can choose to stay original, or you can switch to radial tires. Speedway Motors carries both styles in a vintage look from brands like Coker Tire and Radir Wheels, and you can usually find a direct replacement for your vintage tire. Should you choose to make the change to a radial tire, you can use the chart below to find the closest size to match your original. (Please note: these sizes are as close as we can get, however they are still an approximation.)

Bias Ply to Radial Tire Conversion Chart
P-75 series

(NOTE: On the 83 Bias Ply, there is sometimes a decimal point, i.e. 7.00-14, it varies with manufacturer)

  • So, referring back to our original tire size of 700-14, we can see that an appropriate size that will be close to the original will be either a P195/75/14, or a P205/70/14.

  • To find whether the tire will “look right” or fill the original wheel well like the OEM tire did, you can calculate the overall height of the tire and see if it comes close to the replacement. All you need is the “P-size” of the tire. The formula to do this is as follows:

So with a tire size of P225/50R16…

Products Featured in this Article

Related Articles

Racing Helmets: What You Need to Know for Proper Fit, Use, and Care
by Mark Houlahan - Posted in Tech
If you’re planning to participate in any motorsports activity you need to be aware of the safety helmet requirements and what helmet features are best for the particular activity you’re involved in.
What Is Positraction and Do You Need It?
by Mark Houlahan - Posted in Tech
Posi, limited slip, Traction-Lok, or whatever your favorite brand calls it is how your rear axle provide equal traction to both tires, and trust us, you’ll need it! So, read all about posi units and their benefits here in our guide.
Install Guide: Upgrading a 5.3 LS With a Cam Swap
by Joe McCollough - Posted in Tech
An LS cam swap can yield big power gains. And, you can do it at home. Here's how...
Modern Steering Wheels With Classic Styling
by Joe McCollough - Posted in Videos
Looking to change that old steering wheel out for something that's a better fit in your hot rod or classic? Speedway Motors offers a wide variety of steering wheel styles that look right at home in your vintage interior.
C10 LS Swaps Made Easy with Motor Mount and Transmission Crossmember Kits
by Joe McCollough - Posted in Videos
Looking to update that '67-'72 C10 truck with an LS swap? These motors mounts and transmission crossmember kit will make that modern powerplant and transmission fit like they came that way from the factory!
How To Replicate LS Engine Dimensions with a Steel LS Mock Up Block
by Joe McCollough - Posted in Videos
The new Steel LS Mock Up Block from Speedway Motors makes it easy to fab mounts and check clearances while LS swapping your car.
Easily Back Your LS Swap with The Manual Transmission of Your Choice
by Mark Houlahan - Posted in Tech
Leave all the head scratching to us, as we have your manual transmission bellhousing solution for your LS swap all figured out already
The Best Wiring Solution for Your Hot Rod or Muscle Car Project
by Mark Houlahan - Posted in Tech
Electrical wiring is one of those tasks that enthusiasts dread tackling on their own. We're here to tell you that wiring your project vehicle is something you can do with a little help from your friends at Speedway Motors!
How to Lower C10 Front Suspension with Drop Springs and Spindles
by Joe McCollough - Posted in Tech
Watch as we install a front suspension lowering kit on our 1968 Chevy C10. Upgrades include disc brakes with a 5 on 5” bolt circle as well as 2” drop springs and 2 ½” drop spindles.
How to Measure and Cut 9 Inch Ford Axles
by Joe McCollough - Posted in Tech
In this video, we go through the process of measuring and cutting 9" Ford axles.