SELECTING CUSTOM WHEELS AND TIRES FOR YOUR CORVAIR

[bbodie52]

I posted this information elsewhere, but I felt that posting it here too as a long-term reference would be useful. I also added an example to illustrate the process...

Since none of the big wheel and tire retailers know anything about Corvairs , the Corvair owner has to do the research and calculations to tell the retailer what the Corvair needs. Careful research is needed so you don't end up with any "surprises" when the tires and wheels arrive. They can be difficult to return or exchange if they don't fit -- especially when the sizing choices were made by you and not based on a salesman's recommendations! Salesmen and retailer technical "experts" can tell you about quality, warranties, sale pricing specials, and general road performance characteristics, but they cannot tell you about non-standard sizing for your Corvair.

Actually, the database on tires and wheels on the Tire Rack website is extremely useful, once you determine several critical factors, including:

WHEELS

1. Diameter
2. Width
3. Backspacing
4. Lug Pattern

TIRES

1. Rim Diameter *
2. Rim Width *
3. Desired Overall Outside Diameter **
4. Calculated Revs per Mile **
* Tires sized to meet selected wheel specifications
** Aspect ratio and tire profile selected to maintain correct operation with Corvair differential final drive ratio and speedometer accuracy requirements. This information can be found for each tire in the Tire Rack online database.

Use the information on the following website to determine the desired wheel and tire sizing for your Corvair.

SIZING CORVAIR WHEELS AND TIRES
http://autoxer.skiblack.com/tires.html

Then use the data on the Tire Rack online database to select your wheels that meet your Corvair's needs and your styling and pricing preferences. Finally select tires to match your Corvair's needs, selected wheel sizing, and your preferences for tire handling, weather, and wear performance and pricing. Now you have the desired wheels and tires that match each other and your Corvair's technical needs too.

http://www.tirerack.com
The Tire Rack database can help you to select proper wheels and tires to match the above parameters. Their consumer feedback and tire reviews can help you to select performance, pricing, wear performance, etc. to meet your desired expectations and driving habits.

Here is an example of the process...

My Current tire sizes on my 1966 Corsa are:

Current Tire Product and Size:
Front: Goodyear Eagle ST P195/70 R14
Overall Diameter: 24.8" Revs per Mile: 839
Rear: Goodyear Eagle ST P235/60 R14
Overall Diameter: 25.1" Revs per Mile: 829

I found the Overall Diameter and Revs per Mile numbers on the Tire Rack by selecting my current tire sizes, and then looking them up on current Tire Rack listings...

Next, I chose some wheels I might be interested in. In this example, I started with wheels offered for a car that could be a GM donor vehicle for a LM Corvair -- a Pontiac Firebird. I chose a 17x7" or 17x8" rim in this example that had the correct lug bolt pattern of 5 lug 4 3/4" (5-475) and wheel backspacing or 4" to 5"

The Tire Rack recommended tire size for these wheels was 2.45/45-17, but I discovered that this size has Overall Diameter and Revs per Mile numbers that were too high for my Corvair, so I looked at other sizes that were similar to the size recommended by Tire Rack for these wheels, but also closer to the specs needed by my Corvair. A good compromise size is seen below.

REAR WHEEL AND TIRE SELECTION
The 2.25/45ZR-17 has an overall diameter of 25", which is very close to the 25.1" overall diameter of my current 14" rear tires. 833 Revs per Mile is also very close to my current rear tires, which provide 829 Revs per Mile. The Michelin tires in this size will also tolerate a 7" to 8½" rim width, so this tire would work on my Corvair rear using either a 17x7" or 17x8" wheel which gives me 4.02" or 4.52" backspacing (also in the desired range for my Corvair).

FRONT WHEEL AND TIRE SELECTION
The 2.15/45ZR-17 has a slightly smaller overall diameter of 24.7", which is close to my current 14" front tire overall diameter of 24.8". 844 Revs per Mile is also close to my current front tires, which provide 839 Revs per Mile. This will help with body clearance and speedometer accuracy on the front of the LM Corvair. These Michelin tires in this size will also tolerate 7-8" rim width, according to the Tire Rack chart, so they will fit on the selected rims in either 7" or 8" widths.

FINAL CHOICE?
A conservative choice would be to use the smaller 2.15/45ZR-17 tires all around, mounted on the narrower 17x7" wheels. This provides 4.02" backspacing and are less-likely to be problematic than the wider 8" wheels or the slightly larger tires in the final installation. The larger sizes would likely fit OK on the rear of the 1966 Corvair, but doing so eliminates the possibility of tire rotation to promote more-even tire wear.

Alternately, the 8" wide wheels might work all around, with the wider tires on the rear, or the smaller tires all around to permit tire rotation. The 8" wide wheels have about ½ inch more backspacing, which seems to be the "sweet spot" to promote better steering feel and clearance. But care must be taken when fitting these more extreme wheels and tire sizes to avoid body or suspension interference problems. Some body modifications or suspension mods might be necessary.

Tire and wheel sizing for your Corvair can be a somewhat long and tedious process. If you find another Corvair owner who has similar wheels with the same diameter, backspacing and rim width, you can safely duplicate that person's Corvair wheel and tire sizing on your own Corvair, if your car is the same model year series and has similar suspension characteristics. Otherwise you will need to do your own careful numbers crunching to find the right wheel and tire combination in 14", 15", 16", or 17" sizes for your Corvair.

Some aspirin or Tylenol might also help.

[bbodie52]

Here is some additional information I compiled regarding overall tire diameters and tire revolutions per mile that may be of use when selecting a wheel and tire size for your Corvair...

The size radial closest to a stock 6.50-13 bias ply is 185/80R13, yet searching the entire Tire Rack database for that size only produces two tires... a Goodyear Marathon Radial and a Power King Towmax STR — both of which are TRAILER SERVICE TIRES ONLY! Although 13" tires can be obtained from other sources that would be suitable for passenger car service and will support the needs of a Corvair in the original stock size, it is becoming somewhat obvious that the original size tire specified for the Corvair has become a severely limited market size, and that most modern technology radial automotive service brands will not see production in this size.

That being said, here are some significant specifications for this tire size...

185/80R13
— Rim Width Range: 4.5" - 6"
— Cross-section Width (Measurement from the inner sidewall to the outer sidewall): 7.2"
— Overall Diameter: 24.7"
— Revs per Mile: 848

Revolutions per mile. Stock is 853 (to 1965) and 833 (1966-69 and wagons) revs/mile, according to Chevy specs. Oddly enough, the calibration for the speedometer doesn't quite match — the '66 up speedos are set for 825 revs/mile.

For comparison, here are the specs for 14" wheels that I am currently running on my 1966 Corsa convertible...

Front: P195/70 R14 — Overall Diameter: 24.8", Revs per Mile: 839, Section Width: 7.9"
Rear: P235/60 R14 — Overall Diameter: 25.1", Revs per Mile: 829, Section Width: 9.5"

Here are some sizes that should work on Corvairs, given a proper wheel width, offset and back spacing (revs per mile for each size are shown in brackets. The range shown reflects different manufacturer specifications):

P185/70R14 (all) [856-866]
P195/70R14 (all, good replacement for 1960 - 65 6.50-13) [839-843]
P205/70R14 (all, good replacement for 1966 - 69 7.00-13) [821]
P205/55R15 (all) [843-874]
P195/60R15 (all, good replacement for 1960 - 65 6.50-13) [859-864]
P195/65R15 (all, good replacement for 1966 - 69 7.00-13) [832-840]
P205/60R15 (all, good replacement for 1966 - 69 7.00-13) [842-846]
P205/55R16 (a little tall, may rub on an early, fits lates) [831-840]

Late models have a little more room in the rear, you could use these sizes on the rear of a late if you want the "big and little" look:
P225/60R14 [842]
P235/60R14 [829]
P215/60R15 [818-837]
P225/50R16 [831-837]

NOTE: ALL OF THE ABOVE RECOMMENDED TIRE SIZES WERE DRAWN FROM THE FOLLOWING WEBSITE:

SIZING CORVAIR WHEELS AND TIRES
http://autoxer.skiblack.com/tires.html

You can see by these numbers that you can play with a broad range of tire sizes and diameters and stay close to the original 13" tire specs in revs per mile, or increase that overall diameter to some extent to make some minimal adjustment to the engine speed at a given vehicle speed (revs per mile). A greater impact might be made by changing the gearset in the differential, but such a change means a significant amount of work involved (if the gearset is compatible with the differential).

Adjusting tire brands, performance specs, and size has a much-greater impact on handling and braking performance than it will on fuel mileage or engine speed. These numbers only list wheel sizes from 13" to 16", and tire aspect ratios down to 50, but lower profile tires and wheels up to 17" in diameter have been successfully fitted to Corvairs. These numbers give you some idea of what will fit, but tread width and wheel width/back spacing must also be carefully considered to ensure adequate clearance with suspension components and the car body.

[bbodie52]

Here is another very useful link to help you to determine proper tire and wheel sizing for your Corvair (and other cars too, if you choose to drive something else!)

Good Wheel and Tire Conversion Tool

http://www.rimsntires.com/specspro.jsp

Info provided by Rob (SyntheticBlnkerFluid) in Chebanse, IL

[Skrain]

If you want to stay with the 13" wheels, a good source to look for tires is Coker Tires, in Chattagooga, Tn.
They have tires for classic, antique and older cars.
I bought my P185.80R13 B.F. Goodrich Silvertown radials from them. They had those listed, as well as a Maxxis tire in that size.
http://www.cokertire.com/" onclick="window.open(this.href);return false;

[terribleted]

Big and little setups can be a pain to find tires for. A car I have here now is using 225/50/15 rears and 205/55/15 fronts. The look and clearance is excellent. At this time however no one seems to make these 2 sizes in a particular line of tires, so in order to replace with similar sizes will involve 2 different tire patterns from a single brand or 2 similar tire patterns from different brands. The 205/55 is mostly not offered in a sporty performance tread any more and the 225/50 is mostly only available in off road racing designs. Options a little larger (existing are a touch small diameter wise) help but are not much better. Getting so even 15" are tough:)

[County98]

Excellent compilation Brad. Thanks!

TerribleTed, Those are exactly the tire sizes I picked out to put on my Craigslist Camaro wheels I picked up. The Falken Zeix 912 is available through Discount Tire Direct in both sizes and all match. Tire height front and rear comes in at 23.9". Just in case you're looking for a set.

-Shayne

[bbodie52]

Here is some additional information I compiled regarding street tire availability in 13" diameter from two major tire vendors, as of June 2014...

Some bad news (at least for the 13" tire crowd). Below is a listing of all of the tire sizes offered by the Tire Rack in 13" diameter. Skipping past the first two because of the very narrow size (105 and 155), only two of the remaining sizes list tires for use on the street. Both of those are in blackwall. There is nothing in Raised White Letter (RWL) in 13" at all. All of the other sizes are for trailers or for racing only.

Tire Sizes by Wheel Diameter

Options in 13"
105/80-13, 175/80-13, 185/80-13, 225/45-13
155/80-13, 185/60-13, 205/60-13, 225/50-13
175/70-13, 185/70-13, 215/50-13, 255/40-13

175/70R-13
4 CHOICES — BLACKWALL ONLY
Kumho Sense Grand Touring All-Season, General AltiMAX RT43 (T-Speed Rated) Standard Touring All-Season,
Kumho Solus KR21 Standard Touring All-Season, Michelin Defender Standard Touring All-Season

175/80-13
2 CHOICES — TRAILER SERVICE ONLY

185/60-13
3 CHOICES — RACETRACK AND AUTOCROSS ONLY — BLACKWALL ONLY

185/70R-13
1 CHOICE — BLACKWALL ONLY
Kumho Solus KR21 Standard Touring All-Season

185/80-13
2 CHOICES — TRAILER SERVICE ONLY

205/60-13
5 CHOICES — RACETRACK AND AUTOCROSS ONLY — BLACKWALL ONLY

215/50-13
1 CHOICE — RACETRACK AND AUTOCROSS ONLY — BLACKWALL ONLY

225/45-13
6 CHOICES — RACETRACK AND AUTOCROSS ONLY — BLACKWALL ONLY

225/50-13
2 CHOICES — RACETRACK AND AUTOCROSS ONLY — BLACKWALL ONLY

255/40-13
1 CHOICE — RACETRACK AND AUTOCROSS ONLY — BLACKWALL ONLY

Street Tires

Let's look at street tires first. I use and recommend only radial tires, so that's what this information covers. The size radial closest to a stock 6.50-13 bias ply is 185/80R13, but unless you have a factory stock show car, you may wish to use a different size.

There are a few vendors — particularly those who cater to classic car owners — who offer some additional special tires in 13" diameter. But generally high performance modern radial tire offerings that take full advantage of modern technologies and engineering advances are not offered in the obsolete 13" diameter.



For comparison, here is what I could find in the 13" diameter size at Discount Tire...

Discount Tire does not list Corvairs as valid 1960-1969 Chevrolet vehicles anymore.

Going by size only, there are a few extra choices in the 175/70R-13 and 185/70R-13 sizes...

175/70R-13
6 CHOICES — BLACKWALL ONLY
Geostar Remex RX-615, GT Radial Champiro VP1, Falken Sincera SN-828, General Altimax RT43, Kumho Solus KR21, General Altimax RT

175/80-13
5 CHOICES — TRAILER SERVICE ONLY

185/60-13
0 CHOICES

185/70R-13
5 CHOICES — BLACKWALL ONLY
Geostar Remex RX-615, Nankang CX-668, GT Radial Champiro VP1, Falken Sincera SN-828, Kumho Solus KR21

185/80-13
4 CHOICES — TRAILER SERVICE ONLY

205/60-13
0 CHOICES

215/50-13
0 CHOICES

225/45-13
1 CHOICE — RACETRACK AND AUTOCROSS ONLY — BLACKWALL ONLY

225/50-13
0 CHOICES

255/40-13
0 CHOICES

[California Dreaming]

P185/80r13 Whitewall Tires AVAILAIBLE !!!!!!!!!!!!

I bought these 5 years ago at Pep Boys.... buy 4 get 1 free.. You can still find them online at several places..... here's amazon....

https://www.amazon.com/P185-80R13-Maxxi ... ewall+tire

[bbodie52]

The BF Goodrich Size P225/60R14 has the same Overall Diameter and Revs per Mile as the 185/80R13 tire, but a tread width of 7.6", compared to the narrow tread of 4.7" on the 13" Maxxis tire! The low profile 13" BF Goodrich tire has a smaller diameter than the Maxxis tire, but a wider treadwith for more traction and improved braking.

Sizing Corvair Wheels and Tires
http://autoxer.skiblack.com/tires.html

For a few dollars more I believe the BF Goodrich Radial T/A offers the Corvair much better handling and braking performance on the street. The Maxxis tire offers an original look with similar performance to the 1960s vintage tire.



RADIAL T/A - SIZE: P205/60R13
Performance All-Season
https://www.tirerack.com/tires/tires.js ... &tab=Sizes
Per Tire:
$123.54

Availability: In Stock

...I surfed over to The B.F. Goodrich site to come up with some examples of tires that would work well on Corvairs. They have data sheets for all of their tires there, I used the specs from the Radial T/A here, other models will be a bit different. You should be aware that the sizes are a range, so it's a good idea to get the data sheet if you can, especially if you have chosen a size near the limit of what will fit. Unfortunately, BFG doesn't offer a 13" Radial T/A that will work well, these are 14, 15 and 16 inch:

P185/70R14 (all)
P195/70R14 (all, good replacement for 1960 - 65 6.50-13)
P205/70R14 (all, good replacement for 1966 - 69 7.00-13)
P205/55R15 (all)
P195/60R15 (all, good replacement for 1960 - 65 6.50-13)
P195/65R15 (all, good replacement for 1966 - 69 7.00-13)
P205/60R15 (all, good replacement for 1966 - 69 7.00-13)
P205/55R16 (a little tall, may rub on an early, fits lates)
Late models have a little more room in the rear, you could use these sizes on the rear of a late if you want the "big and little" look:
P225/60R14
P235/60R14
P215/60R15
P225/50R16

Sizes Currently Available...

13

• P205/60R13

14

• P205/70R14
• P215/60R14
• P215/70R14
• P225/60R14
• P225/70R14
• P235/60R14
• P245/60R14

15

• P155/80R15
• P195/60R15
• P205/60R15
• P215/60R15
• P215/65R15
• P215/70R15
• P225/60R15
• P225/70R15
• P235/60R15
• P235/70R15
• P245/60R15
• P255/60R15
• P255/70R15
• P275/60R15
• P295/50R15

TIRE SPECS - SIZE 185/80R13
SECT WIDTH: 7.2" TREAD WIDTH: 4.7" OVERALL DIAM: 24.7" REVS PER MILE: 842


LEFT-CLICK IMAGE TO ENLARGE, AND CLICK A 2ND TIME FOR MAXIMUM ENLARGEMENT

BF Goodrich Radial TA Tire Specifications