True, but with only NA power it'll likely be slower compared to something a little narrower due to the extra weight, extra drag and extra rolling resistance. For the street on a modestly tuned NA 225's are plenty.

Also, while the parts may be cheap, unless you do all the work yourself the bodywork and install costs can quickly get out of hand.

 

But with wide front fenders we would start trying to squeak by with 265 or 275 up front :P

245 all around on stock fenders no rub when racing= done.

275 all around with +30mm front fenders?

The math says YES, I say HELL YES make 'em DOT Rs to boot!

If you can max the negative camber at the strut top with some mods and then adjust the negative camber out w/ eccentric bolt at the hub carrier or re drill the strut housing you have freed up some room inside AND corrected for lower than stock offset.

Probably shooting for +25 offset as that gives you +20mm wider on outside and +10 wider on inside than the 245 +30 offset that is known to work.

All that work because the math lies and the +30mm front fenders are like +22mm

See, wide fenders won't stop the madness...

 

yeah that is true, most front wide fenders barely fit a 255 on a 17x9 +15 especially for a hard driven track setup.

I hear ya guys, and I do agree with a mild n/a setup, the 225s all around is pretty nice. a friend of mine had a very modded n/a '87 lightweight base model on some 11pound 15x6.5 wheels and 225s all around and it was so nimble it felt incredible in the twisties and that lightweight wheel setup helped the car keep weight down to 2350, for a street car with full interior too!

 

I know that on NA Miatas, unless they're pretty wild, 205's are typically faster around the track than 225's. On really tight tracks 225's can be better, but they definetely loose out on the straights. This has been tested and verified.

Especially if we're talking track use then 225's would be best, as you can get 225/45/15 or 225/50/15's which are smaller (better gearing) and lighter than just about anything wider.

 

definitely, much lighter and less air resistance since they are not super wide.

 

Our fastest Miata(and often top time of day car) runs 235 all around on a 9lb (Lenso VPD)13x7.5 rim and it is an NA Street Prepared car.

The out of area Miata people tell them it would probably do better with a skinnier tire, but still can't come close to catching up to it- LOL

We have a lot of gravel and uneven, chunked asphalt though so the lighter the car and wider the tires the faster no matter how underpowered.

My 36HP flywheel Honda N600 had a hard time hooking up with 165 wide A008. Thinking of running it in STS as it is 1300lb and allowed a 225 tire. Found a couple manufacturers of 225/40-10 and 225/40-8 DOT legal race tires...

Now on the hillclimb it is another matter. I believe ScrapFC was very close to the same time with skinny 300? treadwear on stock rims and his 255 RT-615 on 9" wide RPF1 rim.


Hmm, for Auto-x the new 275/35-15 would fit nicely up front with +30mm fenders as you could run the +30 to+25 offset and have room inside as wheel and tire would be under the spring and perch on most coilovers.

 

For sure wider is better in autocross, because the corner to straight ratio is a lot higher, so cornering grip is more important than rolling resistance and acceleration and there's much, much less aero drag. When I say that the narrower tires are better I'm meaning on a road course where speeds of over 100mph are hit several times a lap.