More rubber

Short answer: probably not.

Longer answer: you can always get your rears widened and put some bigger/better rubber on. I've got 6" rims and 195/60s fit easily and nicely. I think 205s would work as well. If you get your rims widened, you can also get them recentered.

Phil, ditch the all season tire sand go with the 195/60's like Stan said.  Get a pure summer performance tire.  My 145HP original Subaru motor came with 195/60s over 5.5s and  Yokohama ES100's.  Never had any problems. The 205s work  in the rear but you may need to get your wheels widend  inward. 

I have 8 inches of rubber on the ground but it is also a wide body and I'm running full custom one off rims.
Short answer: probably not.

I had 7inch wide rims rears in my old IM with 4 bolt pattern.   

Dunlop, 185/65 front, 205/60 rear 

They were Mangels custom widened by Henry.  I think those should fit your car... 

Ray 

 P.S.  I also put these on the last season I owned it..

205/60R-15 Yokohama AVS ES100 

Ray,  The AVS ES100's are not available anymore .  

Your right that is the old model... I think the size is still available in Yokos though. Avid Envigor is the new model if I remember right  

They were pretty noisy anyhow.

A 205/60 will fit on a 5 1/2" rim; the question is whether ditching the spacers will be enough, and the answer is probably no, as the tire is 3/4" wider (and that's 3/8" to the outside, so without the spacers it will be VERY close!). You could have them widened (on the inside) to 6 1/2 or 7" though, and it would work (probably with the spacers). As was mentioned, 195/60's will fit on your rims, and may even fit with dropping the spacers, as it only adds 3/16" to each side. The only problem is 3/8" isn't a lot of tire. Al

Just measured the tire to fender distance on both sides in back.  12mm on the right and 6mm on the left.  Hand made car I guess.  So the only thing my spacer is going to give me is an extra 6mm.  Enough to go 10mm bigger in tire width to 195.  Not really worth it.  Maybe I can get some stickier rubber.  Or maybe just slow down.  

I will say that I never got sideways in either of my spyders.  They didn't have much rubber.  Rear broke away in a predictable gradual fashion allowing you to reel the rear in with a little throttle and counter steer.  Fun.

Phil,  good advice you gave yourself  Slow down and get a stickier set of tires . 

Phil, you're a brave man trail braking with a rear-engine car.

As I see it a non-flared speedster has two problems when it comes installing wider rear tires:

1.  Fitting  wider wheels and wider tires on our cars.

2.  Being able to purchase a high performance tire that fits our cars.

Rim width is very important-wider is better.  On my very light track Miata I ran 8 inch wide wheels on all four corners, with 225/45-15 tires.  Other Miata drivers were stuffing 9 inch wide wheels under their fenders to get that extra little handling edge.

Not only do we have very limited space in the rear, but many of our cars don't have the same tire clearance on both sides.  That's something to be cognizant of when considering wider wheels/tires.  What will fit on one side may not fit on the other.

Back in 2010, when my IM was at Intermeccancia, Henry mounted a Porsche Boxster 16x7 wheel, with a 205/50-16 tire, on the back of my IM.  The wheel had a huge offset (some thing like 55mm).  The tire cleared the fender but rubbed on the spring plate bolts.  With a bit of work with spacers I believe I could have got that wheel/tire combo to fit.

The easier, but not cheapest, solution would be to go with a custom made wheel.  That way we could pick the wheel diameter, width, and offset that would best fit our cars.  In my view going with a 15 inch wheel is a waste of time, because the 15 inch tire selection for performance tires is  terrible.

16 inch wheels is the sweet spot and there are still a few 195/205 performance tires available in that diameter.

Ron O posted:

 

... In my view going with a 15 inch wheel is a waste of time, because the 15 inch tire selection for performance tires is  terrible.

16 inch wheels is the sweet spot and there are still a few 195/205 performance tires available in that diameter.

I could not possibly agree more.

Phil, I am running 7.5 inch rear rims with 205's in the rear.  It's needed with 265 hp on tap. 

Stan Galat, '05 IM, 2276, Nowhere, USA posted:

Ron O posted:

 

... In my view going with a 15 inch wheel is a waste of time, because the 15 inch tire selection for performance tires is  terrible.

16 inch wheels is the sweet spot and there are still a few 195/205 performance tires available in that diameter.

I could not possibly agree more.

Me 3...

Phil, you're a brave man trail braking with a rear-engine car. nod

Yes. I learn the hard way I can't drive the 356 the way I used to drive my spyders.