Street Tire Choices:
In 15", readily available street tires in the 295/50x15 size are:
-BFG Radial T/A (S-rated)
-Dunlop GT Qualifier T (T-rated)
-Firestone Firehawk Indy 500 (S-rated)
-Goodyear Eagle GT II (S-rated)
-Yokohama Avid S/T (T-rated)
-Cooper Cobra G/T (S-rated)

 

Here is a size comparison:

1. BFG (S-rated)

Size Service Description Load Rating	UTQG	Max Load	Max. Inflation Press.	Tread Depth	Rim Width Range	Meas. Rim Width	Sect. Width	Tread Width	Overall Diam.	Revs Per Mile
295/50-15  105S  SL	400 A B	2061 lbs.	35 psi	11/32"	8-11"	9.5"	12.2"	9.5"	26.7"	779

2. Dunlap (T-rated)

Service Description Load Rating	UTQG	Max Load	Max. Inflation Press.	Tread Depth	Rim Width Range	Meas. Rim Width	Sect. Width	Tread Width	Overall Diam.	Revs Per Mile
295/50-15  105T  SL	440 A B	2061 lbs.	35 psi	10/32"	NA	9.5"	12"	10.2"	26.6"	786

3. Yokohama Avid (T-rated)

Service Description Load Rating	UTQG	Max Load	Max. Inflation Press.	Tread Depth	Rim Width Range	Meas. Rim Width	Sect. Width	Tread Width	Overall Diam.	Revs Per Mile
295/50-15  105T  SL	420 A B	2061 lbs.	35 psi	12/32"	8-10"	9.5"	12.4"	10.1"	26.7"	778

4. Firestone Firehawk Indy 500 (S-rated)

Service Description Load Rating	UTQG	Max Load	Max. Inflation Press.	Tread Depth	Rim Width Range	Meas. Rim Width	Sect. Width	Tread Width	Overall Diam.	Revs Per Mile
295/50-15  105S  SL	500 A B	2061 lbs.	44 psi	12/32"	8-10"	9.5"	12.2"	9.9"	26.7"	780

5. Goodyear Eagle GT II (S-rated)

Service Description Load Rating	UTQG	Max Load	Max. Inflation Press.	Tread Depth	Rim Width Range	Meas. Rim Width	Sect. Width	Tread Width	Overall Diam.	Revs Per Mile
295/50-15  105S  SL	420 A B	2061 lbs.	44 psi	11/32"	7.5-11"	9.5"	12.1"	11"	26.6"	NA

6. Cooper Cobra G/T (S-rated)

 

 

For pricing of the first 5, see Tire Rack

 

For more info on the Cooper, see Cooper Tire

 

The BFG look good and are fine for street use.  By far the narrowest tread at 9.5”.

 

The GY are the largest at 11" tread width.

 

IRS cars have an easier time fitting the GY because the arms are adjustable and the tire tilts inboard at the top for slightly more clearance.

 

The Avid have a higher speed rating and have gotten good reviews for other roadster users,

see http://www.ffcobra.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=048833#000001

 

1/25/07 update: Another choice, Goodyear Big Letter, now available in Yellow Letters!

Note: On a Mark I or Mark II FFR, the backspace has to be perfect or severe rubbing will happen.

Not recommended unless you have a lot of patience.  On a Mk III FFR, there is more room.

They are these sizes:
26.5x8.0-15 fronts
26.5x10-15 rears

For 15x7.5 front rims and 15x9.5 rear rims

Web site see http://www.rogerkrausracing.com/gyCobra.html

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Another excellent choice is Mickey Thompson Sportsman S/R ("Street Radials")

They are directional, very sticky, and about the same as a 275/50R15 rear.

They are sized as follows
26x10R15 fronts

26x12R15 rears

Sold by Summit Racing, Jegs, eBay, etc.  (warning: not inexpensive)