Rotus 7 - Track width and tire selection?

Howdy all, I'm still going thru the Rotus 7 I bought a few weeks ago, currently waiting on some suspension parts.

The tires currently on the car are over 15 years old (though they look practically new) and the sizes are practically obsolete. I'm trying to figure out the best path forward. Currently the car has 215/50-15 front and 245/50-15 rears, the car weights ~1600lbs and has more than 200hp. It was originally built in the early '90's as a SCCA roadracer, I plan to use it on the street, autox and maybe track days. The front wheels are zero-offset 15x6.5 or 15x7 and the rear are 32mm(1-1/4") negative-offset 15x10 on a 4x4.5 bolt circle.

Hours of web searches tell me there is not much available for sticky, small diameter tires. I've read that 7's are a little more user friendly with 13" wheels, but that's not an option because the front brakes won't allow anything smaller than a 14" wheel. I'm trying to stay close to the current tire diameters.

So that leaves me with 16" wheels with something like 185/ or 195/55-16 fronts and 215/55-16 rears, both will squeeze onto a 16x7" rim pretty well, I think.

I'd like to buy 4 of the same wheel rather than different widths/offsets, but that will reduce the rear wheel track width ~2.5". There aren't a lot of wheel options with the 4x4.5 BC either.

Currently the front track is ~60.75 and the rear is ~60.625, the new wheels would make the rear track ~58.125", wheelbase is ~96"

What are the handling effects of narrowing the rear track?

Will a performance 215/55 tire just go up in smoke all the time with so much HP?  

I want to get as light a wheel/tire combo as reasonably ($$) possible.

Thanks

I was running 225/50-15 square on my 1350 lbs/220HP Birkin S3. ITB'd Zetec. The power is mainly up top, so it didn't overwhelm the tires unless I was hooning in 1st gear or it was wet out. Most 7 guys are running 195 or 205 honestly. I had a hard time temping up a 225. At 80 degree ambients I don't think I ever got a tire face temp over 140 on track.

If you're worried about the rear track width, you can always get a set of beefy bolt on spacers and use those to get it back to where you want instead of using different front and rear wheels.  Of course, that option is probably slightly less strong, but if they're good spacers it shouldn't be an issue. 

The selection of performance tires is actually pretty good at 15" and excellent at 17", but 16" is a no-man's-land, avoid that diameter for sure. A square setup is nice for longevity/convenience of tire rotation, do you know how the handling balance is now? In terms of width, in 15" or 17" diameter you'll have a good choice of performance tires in 7-9" widths, above or below that the options will become scarce.

I have 15x7s on my AE92 and I run 195/50R15 or 205/50R15 tires, I'm aiming to move up to 15x8s and run 225/45R15s with the option of 205/50R15s if I can't get those.

205/50R15 is the Spec Miata takeoff size BTW. If I were you I'd be tempted to try 225/45R15s on 15x9s all-around, you can also run 245-wide tires and to go 15x9.5s or even 15x10s but tires in those sizes are uncommon. You may want to consider going up to 17s for running 245-wide tires.

One more edit: A 245/40R17 has almost identical external dimensions to a 245/50R15, there is a good selection of 200TW and R-comp tires in this size, they will fit well on 17x9s. For the front, you could run the same size or if you want something close in size to your current fronts, you could run 215/40R17s on 17x8s, there are a good few performance tires available in that size too. That is my final answer

Here's my car.

https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/rotuslotus-7-replica-powered-by-a-mazda-13-b-turbo/101891/page1/

I did 15x7 ET15 front and 15x8 ET0 rears with Toyo 888's(205/50-15 front, 235/50-15 rear). My car makes 250rwhp and it could use LOTS more rear tire!

Thanks all for the info! You really helped narrow down my searching. I was thinking 17's would be too large, but  I'll look into it more. Currently the front tire/wheel weights ~35lbs and the rears ~43lbs, hoping to shave a few lbs off that.

Last night it occurred to me to just find 2 15x7-ish wheels for the rear for now and fit any reasonably sized tire for the short term. I'm concerned about one of these tires going flat while I'm trying to sort the motor... no spare, no jack, ~4.5" ground clearance with air in the tires... I have no idea how it handles with it's current set up, pretty poorly I'd guess, based on the play in the upper A-arm...

My wheels are XXR's. Polished lip vs black lip.