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Hey guys,

Anyone on here running 225 tyres on their 5's?

what do you think? I've just had 225's on my NB SP for the past 3-4months and feel like it is too much grip for the power and chassis at the moment.
(no chassis reinforcement except aftermarket front strut bar)

thinking of maybe moving down to 215's or maybe even 205 and stretching them on the 15X8 RPF1's.

Have only done street driving so far but the car is harder to break traction and obviously alot less adjustable mid corner, probably need to get it on the track again to see how it handles cornering at higher speeds.

205s are what 949 recommend on an 8" wheel. It's not a massive stretch, it will make the sidewall a little stiffer, not quite as cushy to ride on but better for cornering. I don't think there is a 215 with the proper sidewall, might be wrong though.

I'm planning on some RPF1s myself (once they get back in stock) and I think I'll run 225s. I want that extra cushion.

The real answer here isn't smaller tyres, it's more power! Turn it up

haha the plan is to turn up a little anyway! but now that I've dríven the car for a few months with the new set of shoes a bit of perspective has kicked in. Don't get me wrong the grip is unbelievable and in fact I seriously struggle to get the rear end loose, basically impossible without going stupid fast on public roads. I feel like the character of the car has completely changed due to the extra rotational mass, my intentions were to improve the character of the car and not change it!

I found acceleration and deceleration is less responsive and obviously everything is working harder to get the extra mass going or slowed down, in a nutshell it feels sluggish. I thought turning up power might help but being a turbo I imagine this means more boost giving me gains in the upper rev range.

If you're on 16" rims, ignore all of the following since I only know about 15" rims and that 17" rims have NO place on an NA/NB:

I used to have a set of 225x45x15 15x8 6ULs with Toyo R1R tyres for the track and still have a set of 205x50x15 15x9 6ULs with Dunlop Direzza tyres for DD.

The 225's looked great but were overkill for DD; the 205 Dunlop Direzzas had plenty of grip on my SE when it was at ~150rwkw and were amazingly good in the wet.

Some tyre fitters wont fit 205s to 8" rims but on the 15x8 6UL, they're a perfect fit - 225s are better suited to the 15x9 6UL rim.
Not sure if this is the case for other rim models.

I'd recommend you run 205s since I doubt you're getting any benefit from 225s DD and they're just adding weight and making it harder to turn (they're also more expensive).

As ManiacLachy said, 215s on 15" rims have the wrong sidewall for NA/NBs, they're too tall and will rub the wheel linings.

205x50x15s are more commonly available, you have more options available, they're cheaper and they fit.

You can also run a narrow+lighter rim on 205s to decrease unsprung weight even more and get some more of that "character"/handling/performance back (and reduce wear on you brakes too).

Hi Mate
I am running RPF1 15x8 with ADO8R 205 50 15
Tyre and Rim weigh 14kg per corner.

When I was searching most people told me if it was a dedicated track car go 225. As a road/ track go 205.
Accelartion and braking is brilliant. Steering very directional. I have the SP as well.

I currently have 225/45-15 Hankook Ventus R3 tyres on 7.5x15 repos on my stock NB8A.
It is definantly over tyred for my DD.
Looks great from the rear.
Nil issues (for me) with inertia resistance and also good in the wet. Quiet and with a slight sidewall bulge, comfortable.

When they wear out will be fitting 205/50-15's.

I've run 225 A050s (Medium) but I prefer to run 215s. Going back to 225s for the softs to see how they are.

Lokiel wrote:I used to have a set of 225x45x15 15x8 6ULs with Toyo R1R tyres for the track and still have a set of 205x50x15 15x9 6ULs with Dunlop Direzza tyres for DD.

I assume you meant 15x8 6ULs here, I know Gina is a Queen these days, but she's no hardparker!

There's actually surprisingly few 205/50/15 tyres in Australia, the Yanks get a good variety, but we're quite limited. Not quite as limited as we are in the 225/45s, but not much better.

Re: sizes and sidewalls etc. (just doing the maths, not taking into account wear and manufacturing tolerance etc)

Standard 195/50/15 = 576mm diameter

205/50/15 = 586mm (+10mm) (1.75%)

215/45/15 = 574.5mm (-1.5mm) (0.26%)

225/45/15 = 583.5mm (+7.5mm) (1.30%)



So by rolling diameter, a 215/45/15 would be just about spot on.
If you can find anybody who makes them.

Other data points:

SEs come with 205/40/17 = 595mm
SPs came with 205/45/16 = 591mm

195/50/15 sounds really tiny.

ManiacLachy wrote:

Lokiel wrote:I used to have a set of 225x45x15 15x8 6ULs with Toyo R1R tyres for the track and still have a set of 205x50x15 15x9 6ULs with Dunlop Direzza tyres for DD.

I assume you meant 15x8 6ULs here, I know Gina is a Queen these days, but she's no hardparker!

yeah, I meant 15x8s on the 205/50/15s

hks_kansei wrote:Re: sizes and sidewalls etc. (just doing the maths, not taking into account wear and manufacturing tolerance etc)

Standard 195/50/15 = 576mm diameter

205/50/15 = 586mm (+10mm) (1.75%)

215/45/15 = 574.5mm (-1.5mm) (0.26%)

225/45/15 = 583.5mm (+7.5mm) (1.30%)

So by rolling diameter, a 215/45/15 would be just about spot on.
If you can find anybody who makes them.

That's the problem with 215s, it's easy enough to find 215/50/15 = 597mm diameter (+21mm) which are too tall

I run 225/45/15 on 8" rims on a standard engine NB8A track car, & think it's over tyred, so would like to try 205's.

205s are what 949 recommend on an 8" wheel

Some tyre fitters wont fit 205s to 8" rims

All the tyre manufacturers info that I can find, say 7.5" maximum rim width for 205's. Has anyone had safety problems with 8"?

RS2000 wrote:I run 225/45/15 on 8" rims on a standard engine NB8A track car, & think it's over tyred, so would like to try 205's.

205s are what 949 recommend on an 8" wheel

Some tyre fitters wont fit 205s to 8" rims

All the tyre manufacturers info that I can find, say 7.5" maximum rim width for 205's. Has anyone had safety problems with 8"?

Never seen/heard any issues with 205s on 8" rims and they're a very popular rim on MX5s in the US, especially on the track and auto-cross where they get their hardest use.

The fact that 949racing actually recommend 205s on their 8" rims should give you peace of mind - Emilio, a track demon, designed the 6ULs specifically for the MX5 so has done plenty of his own testing and this is what he recommends for 6ULs.
I trust his specific knowlege on these rims rather than some generic rules that have been around for decades.

I don't know that you can blindly apply this to other rims though.

Have had Hankook RS3, Nitto NT01 and Nankang AR-1 in 225/45/15 on my 15x8's.
225's are fine on my SE. Tyre sizing means nothing for grip, its the tyre compound that provides that.
None above have even as much grip as 205/50/15 Yokohama A050's anyway.
And Yokohama 205/50/15's are the same width as all those 3 225/45/15's listed so sizing seems to mean nothing either. All 4 have approximately 220mm tread face width.
For reference the RS3's being the only road tyre on the list, I had no problem getting it sideways with those. And my SE would likely still have less power than a standard SP.
With my 205/45/16 RE003's and 205/40/17 KU31's, the car feels under tyred. More so the Kumho's they are just a harder tyre.

Why are so many saying 215/50/15's are too tall and they will rub in the liners?
I have done it with 15x8 +32 rims and had no problems, and my car is pretty low.
I did it with Yokohama A050's which are known to be notoriously larger than they should be. 230mm tread face!!!
I do have a few mods that help with fitment. Offset bushings in the front upper control arms, so no chance of rubbing on the outer metal.
The tyres at the rear just cleared the guard lips and I mean by a width of a sheet of paper, so I rolled them for safety in case alignment was knocked out.

I can confirm that 225/45/16 on a 16x7+40 rim did rub in the liners up front on track, but only with Tein coilovers fitted, with standard SE Bilstein setup, it did not rub. The rears did just touch those half mud flap things under full load.
They are the same rolling diameter as the popular track size 225/50/15 for reference.
I have a little hole on my left front liner and rub marks on my right to remind me of that and why I don't go to 225/50/15 on my 15's.