Mustang MonthlyHow To Wheels Tires
Choose The Right Tires
Making the most of where the rubber meets the road
Twenty years ago, when concours restorations dominated the hobby, tire selection was simple. You chose either reproductions of the original-equipment tires from Coker Tire and Kelsey Tire or you installed a set of radials that looked close in appearance to original equipment--a modern radial tire with the correct-width whitewall band. Owners of '69-'73 Mach 1s or Bosses who wanted to drive their cars opted for BFGoodrich Radial T/As or Goodyear Eagle STs with raised white letters instead of the factory-original Goodyear Polyglas or Firestone Wide-Oval bias-belted ones.
How do you choose the right tire for your vintage Mustang in 2005? It boils down to how you intend to drive your car. Because the world of classic Mustangs has changed so much over the past 15 years, the questions are more involved. In the past, owning a classic Mustang meant restoring it to factory original condition. It was a serious political issue for many because modifying a classic Mustang was politically incorrect for the times. This kept tire selection simple. Concours-restored trailered cars were fitted with reproductions of their factory-original tires. Many '65-'66 Mustangs were fitted with Firestone Champions or Deluxe Champion reproduction bias-ply tires from Coker Tire. Some got the BFGoodrich Silvertowns, Goodyear Power Cushions, or Generals. Others got Firestone or US Royal Redline reproductions.
If you had something like a '69-'70 Mach 1 or a Boss 302, your Mustang would have been shod with Goodyear Polyglas tires. They worked well for Mustangs that weren't driven often. Bias-ply tires offered more than their share of surprises for those of us who had been driving on radial tires because bias-ply tires are a whole different animal.
If you're restoring a classic Mustang to factory-original condition and intend to show in Mustang Club of America concours-judged competition, tire selection becomes simple. You'll fit your Mustang with reproductions or new-old-stock tires like it came with from the factory. But if you visit your local BFGoodrich, Firestone, or Goodyear dealer, you won't find Champions, Deluxe Champions, Silvertowns, Power Cushions, or Polyglas tires on display. You won't find them back in the warehouse either. These tires are now available from two companies--Coker Tire and Kelsey Tire--depending on what you want to install.
Concours restorations mandate exactly what was on the car from the factory for a given model year. Your '65 Mustang hardtop with a 289-2V V-8, for example, should have either 7.00x13 or 6.95x14 Firestone Champion bias-ply tires to achieve the blessings of MCA show judges. These skinny, pizza-cutter tires aren't much for handling. In fact, after years of radial-tire driving, you'll have to readjust your driving technique with bias-ply and bias-belted tires. Take a corner aggressively and you can count on a trip through your neighbor's flowerbed. Despite that risk, there's nothing quite like a concours-restored classic Mustang perched on four factory-correct tires. Follow the judging rules developed over 30 years of Mustang Club of America restoring and showing to make these cars truly authentic restorations.
Tire technology has evolved dramatically through the years. When vintage Mustangs were new, they were fitted with dinky bias-ply tires. They're called "bias-ply" because their plies run diagonally at a 45-degree angle to the direction of tire rotation. Bias-ply tires evolved into bias-belted tires during the '60s. They are basically bias-plies with additional belts over them for added strength and puncture resistance. The Firestone Wide-Ovals and Goodyear Polyglas tires are bias-belted.
Michelin pioneered radials in the '60s. They differed from bias-belted because their belts were wrapped at a 90-degree angle to the direction of rotation, hence the name "radial" tire. The objective with a radial tire is to keep as much contact patch with the road as possible. This happens via the radial design and flexible sidewalls. Through the years, there have been fiberglass-belted and steel-belted radials. Today's radial tires typically offer a combination of both.
Tire sizing can be confusing. If your '65 Mustang was designed for 6.95x14 tires, what do you install on it now? In 1965, tire sizing was based on section width and wheel diameter. A 6.95x14 tire was 6.95 inches wide (sidewall to sidewall) around a 14-inch-diameter rim. A 7.00x13 tire was 7.00 inches wide around a 13-inch-diameter rim, and so on.
Beginning in 1968, tire manufacturers went to an alphanumeric system of tire sizing that started at the beginning of the alphabet with the smallest tire size. For example, a C78x14 tire was the direct replacement for a 6.95x14 tire. The D78x14 tire replaced the 7.35x14 tire size. The E78x14 became the replacement for the 7.50x14, the F78x14 replaced the 7.75x14, and so on. None of these sizes was an exact replacement, as there was some variation. The two-digit number was the aspect ratio, which is the tire's height (tread to bead) to the section width. This means a 78-series tire is wider than an 84-series tire. That said, a 60-series tire is wider than the 70, 78, or 84.
When radial tires came along in the late '60s, the alphanumeric system of sizing took on the letter R to indicate a radial tire. For example, an F78x14 became an FR78x14.
During the '80s, tire sizing changed yet again with the P-Metric system of tire measurement. Using the example P195/78R14, P means passenger car. Next, 195 means section width in millimeters. The 78 is the aspect ratio, just like the 78-series tires. R means radial construction, and the 14 means rim diameter in inches.
In more recent years, tire manufacturers have gone to the ISO (International Standard Organization) Metric system of tire sizing. It's similar to the P-Metric system originally used in Europe. The ISO system sizes tires the same way as P-Metric, but with the addition of load index and speed ratings after the tire size. You'll see 195/78R14 82H. The two-digit 82 is the load index, or how much weight the tire is designed to carry. The letter H indicates the speed rating, or how fast the tire is designed to go.
What does all this mean when trying to properly size P-metric and ISO Metric radial tires to a classic Mustang? Your Mustang's original 6.95x14 tire size is easily converted to P-metric sizing. First, the aspect ratio of your Mustang's 6.95x14 tire sizing is around 83. All we have to do now is convert 195 millimeters to inches. One inch amounts to 25.4 millimeters. With that in mind, 195 millimeters is 7.68 inches. This is nearly three quarters of an inch wider than the 6.95-inch width of our Mustang's original tires.
The next P-metric size down--which is 175 or 175 millimeters--amounts to 6.89 inches, which isn't wide enough. So, stick with the 195s for best results. This works when we want to install P-metric whitewall radial tires on our classic Mustangs. We have to get it as close as we can, even if it means going a tad larger.
Through the years, we've learned that P195/78R14 and P205/78R14 are ideal Mustang tire sizes if you're seeking original outside-diameter tire sizing. This keeps tire height close to original and your speedometer reading close to accurate. The P195 is closest when it comes to speedometer accuracy.
Performance Mustangs, like the Boss 302, 429, and 351, perform best with P215 or P225/60R15s. Mach 1s and GTs originally fitted with E70 or F70x14 tires will live happily with P215 or P225/70R14s or 15s. It's a good idea to fit-check any tire you're thinking about buying before committing to the expense.
When You Intend To Drive It
Occasional weekend drivers that are also concours-restored rides can get by with bias-ply or bias-belted original-equipment tires. The downside to those dated tires is handling and wear. Bias-ply tires last an average of 12,000 miles. Bias-belted tires don't last much longer because they're made from a softer rubber compound to deliver a smoother ride. Because their sidewalls don't flex in the corners, the contact patch experiences a lot of friction and twist, which increases heat and wear. When you've been driving on radial tires for the better part of three decades, bias-ply and bias-belted tires can be a bit of a shock because they don't drive anything like a radial tire. Those old-style tires are unforgiving of sudden corners and over-correction. They'll get away from you in a hurry, potentially putting you and your Mustang in harm's way.
Driving a classic Mustang with bias-ply or bias-belted tires calls for driving with your mind way ahead of the vehicle. Response time with bias-ply and bias-belted tires is considerably slower.
With this in mind, how do you intend to drive your Mustang? If it's every weekend, consider purchasing radial tires that blend well with the car's factory-original persona. We suggest radial tires in the correct size, with the right sidewall, for improved handling and longevity. For improved handling, you might want to widen the tire's contact patch. For example, a 70-series tire instead of a 78 or an 83.
Tire wear and reliability are the direct result of proper maintenance. Tire inflation is the single, greatest reason why tires wear and fail. Underinflation causes tires to overheat and wear out more quickly. Keep them properly inflated and check tire pressure frequently.
Proper rotation is the second greatest contribution you can make to tire life. Keep them rotated and your Mustang's front end in proper alignment. Bias-ply and bias-belted tires are rotated in a criss-cross fashion just like your grandfather taught you. Radial tires should be rotated front to back, and vice versa, on the same side every 8,000 miles. No matter what anyone tells you, including your local tire dealer, criss-cross rotation of radial tires causes cupping, cord shift, and uneven wear. We base this on 30 years of experience driving on radial tires. The tire direction must remain the same throughout the tire's service life. Criss-crossing radial tires from side to side will ruin the tires, and you'll never get them to balance and ride smoothly.
Along with proper rotation and inflation, get your tires dynamic-balanced whenever they're rotated and the front end is aligned. Out-of-balance tires are unpleasant and unsafe.
ORIGINAL SIZE AND TYPE
When the Mustang was introduced early in 1964, tire sizes were modest. As you can see, Mustang tire sizes and types became more aggressive as time went on and engine sizes increased. As time passed, Mustang witnessed the introduction of wider bias-belted and radial tires.
1965 Standard Suspension Handling Package GT Equipment Group Tire Size 170ci 200 Six 260-2V 289 V-8 260 V-8 289 V-8 6.50x13 in. Std. Std. Std. Std. 7.00x13 in. Opt.* Opt.* 6.50x14 in. Opt. Opt. Opt. Opt. Std. Std. 6.95x14 in. Opt. Opt. Opt. Opt. 5.60/5.90x15 in. Opt. Opt. *Standard with air conditioning 1966 Standard Suspension Handling Package GT Equipment Group Tire Size 200 Six 289 V-8 289 Hi-Po 289 V-8 289 Hi-Po 6.95x14 in. Rayon Bias-Ply Std. Std. Std. 6.95x14 in. Nylon Belted Opt. Opt. Opt. Std. Std. 6.95x14 in. Premium Nylon Belted Redline Opt. Opt. Opt. 1967 Standard Suspension Handling Package GT Equipment Group Tire Size 200 Six 289 V-8 289 Hi-Po 390 Hi-Po 289 & 289 Hi-Po 6.95x14 in. Std. Std. Std. 7.35x14 in. Opt. Opt. Opt. F70x14 in. Opt. Opt. Std. Std. 1968 Standard Suspension GT Equipment Group Tire Size 200 Six 289/302 390 427 302 390 Hi-Po 427/428 6.95x14 in. Std. Std. 7.35x14 in. Opt. Opt. Opt. Std. E70x14 in. Opt. Opt. F70x14 in. Opt. Opt. Std. Std. Std. Std. FR70x14 in. Opt. Opt. Opt. Opt. Opt. 185xR14 in. Opt. Opt. Opt. Opt. Opt. 1969 Standard Suspension GT/Mach 1 Tire Size 200 Six 250 Six 302 351/390 BOSS 302/429 428CJ All V-8 C78x14 in. Std. Std. Std. E78x14 in. Opt. Opt. Opt. Std. E70x14 in. Opt. Opt. F70x14 in. Opt. Opt. Std. Std. FR70x14 in. Opt. Opt. Opt. F60x15 in. RWL Std. 1970 Tire Size 200 Six 250 Six 302 351 428 CJ BOSS 302/429 Mach 1 E78x14 in. BSW Std. Std. Std. Std. E78x14 in. WSW Opt. Opt. Opt. Opt. E70x14 in. WSW Std. w/351 F70x14 in. WSW Opt. Opt. Opt. Opt. Std. w/428 CJ Opt. w/351 F70x14 in. RWL Opt. Opt. Opt. Opt. Opt. w/all V-8 F60x15 in. RWL Std. 1971 Tire Size 250 Six 302 351 429 CJ 429 SCJ BOSS 351 Mach 1 E78x14 in. BSW Std. Std. Std. w/WSW Std. w/WSW E70x14 in. WSW Opt. Opt. Opt. Std. w/302/351 F70x14 in. WSW Opt. Opt. Opt. Opt. Opt. Opt. w/302/351/Std. w/429 SCJ E70x14 in. RWL Opt. Opt. Opt. Opt. Opt. Opt. w/302/351/429 CJ/Std. w/429 SCJ F60x15 in. RWL Opt. Opt. Opt. Opt. Std. Opt. w/302/351/429 CJ and SCJ 1972 Tire Size 250 Six 302 351 351 H.O. Mach 1 E78x14 in. BSW Std. Std. Std. E70x14 in. WSW Opt. Opt. Opt. Std. w/302/351 F70x14 in. WSW Opt. Opt. Opt. Opt. w/302/351 F70x14 in. RWL Opt. Opt. Opt. Opt. w/302/351 F60x15 in. RWL Opt. Opt. Std. Std. w/351 H.O. 1973 Tire Size 250 Six 302 351 Mach 1 E78x14 in. BSW Std. Std. Std. E70x14 in. WSW Opt. Opt. Opt. Std. w/302/351 F70x14 in. WSW Opt. Opt. Opt. Opt. w/302/351 F70x14 in. RWL Opt. Opt. Opt. Opt. w/302/351 F78x14 in. WSW Opt. Opt. Opt. Opt. w/302/351 GR78x14 in. BSW Opt. Opt. Opt. Opt. w/302/351 GR78x14 in. WSW Opt. Opt. Opt. Opt. w/302/351 1974-1978 Tire Size 2.3L 2.8L 302 (Ex. 1974) BR78x13 in. BSW Std. Std. BR78x13 in. WSW Opt. Opt. BR70x13 in. RWL Opt. Opt. Std. CR70x13 in. RWL Opt. Opt. Std. CR70x13 in. WSW Opt. Opt. Std.