Confused: Should I get wider tyres before any engine mods?

CheyneX5 · Postby **CheyneX5** » Thu Sep 06, 2012 3:55 pm

mazmad wrote:wow that's interesting. 8" seems big for 205's, stiffer is better everywhere right...?

It's not unusual. A lot of people run this set up. Here is my car with 15x8 6UL and 205/50R15 RE002.

Suspense · Postby **Suspense** » Thu Sep 06, 2012 4:08 pm

NitroDann wrote:Significant, basically, if any width up to 10" cost the same amount, and you were running 225s (NT01s etc basically stock standard road course tyres for mx5s) you would always always get a 10.

Dann

What does significant mean though? So a 205 on an 8" rim is 'faster' than a 205 on a 7.5", which is 'faster' than a 205 on a 7", which is 'faster' than a 205 on a 6.5", but I'm curious what sort of difference we're actually talking about with the same driver and car. So holding everything equal, including tyre, but changing the rim width.

mazmad · Postby **mazmad** » Thu Sep 06, 2012 4:11 pm

cheynex5 / nitrodann - good info, thanks.

Apu · Postby **Apu** » Thu Sep 06, 2012 4:22 pm

Suspense wrote:
NitroDann wrote:Significant, basically, if any width up to 10" cost the same amount, and you were running 225s (NT01s etc basically stock standard road course tyres for mx5s) you would always always get a 10.

Dann

What does significant mean though? So a 205 on an 8" rim is 'faster' than a 205 on a 7.5", which is 'faster' than a 205 on a 7", which is 'faster' than a 205 on a 6.5", but I'm curious what sort of difference we're actually talking about with the same driver and car. So holding everything equal, including tyre, but changing the rim width.

That's what I think too. It's not going to make enough of a difference for me (or most of us I gather)...plus that little bit of tyre sticking out over the wheel helps protect it from gutter scrapes!

CheyneX5 · Postby **CheyneX5** » Thu Sep 06, 2012 5:19 pm

Maybe the extra sidewall bulge may result in more flex/deformation under heavy cornering load.

Postby **NitroDann** » Thu Sep 06, 2012 5:19 pm

That is correct.

Dann

rascal · Postby **rascal** » Thu Sep 06, 2012 6:33 pm

Suspense wrote:What does significant mean though? So a 205 on an 8" rim is 'faster' than a 205 on a 7.5", which is 'faster' than a 205 on a 7", which is 'faster' than a 205 on a 6.5", but I'm curious what sort of difference we're actually talking about with the same driver and car. So holding everything equal, including tyre, but changing the rim width.

I'd hazard a guess that it might make 0.1 or 0.2 secs per lap. (say 205 on 6.5" to same 205 on 8")
To some that's not worth worrying about for the effort involved in changing rims.
To others that's gold....

Hjt · Postby **Hjt** » Thu Sep 06, 2012 7:32 pm

It makes more difference than that. Think about the gains, then times per corner etc.

It can make seconds of difference. My tyres are different compounds so its hard to judge with no.controls.

sailaholic · Postby **sailaholic** » Thu Sep 06, 2012 8:12 pm

Pretty sure the info is available either through 949 website or miata.net or miata turbo. I could use Google to search and copy a link, but I'm not that motivated on a phone...

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Hellmun · Postby **Hellmun** » Thu Sep 06, 2012 9:59 pm

If your only just starting it won't matter, you'll be barely faster on expensive wider tyres than on cheap street tyres. Have you been on the track before and if so how fast in what kind of car?

If you havn't just get good pads, brake fluid and an open mind. There is a lot to learn to make a modified car fast and tyres/wheels are only one small part that isn't worth getting fixated on yet.

That said the 15*8's will serve you well if your after lap records later on and will happily hold cheaper 205's for now. 225/45/15's are hard to get here and 225/50/15's while more available are very big on an NB which is something you should keep in mind (you'll need camber, guard rolling and the guard linings removed....and that's with stiff suspension). Before someone mentions the Nitto's NT01's I don't believe there road legal in Aus which makes them slick equivalent in the mx5 club classes. Last I spoke to Kumho they weren't bringing 225/45/15's in anymore and even when they did they were pricey at $380 ea. The 225/50/15's are made by Bridgestone, Yoko and Kumho though.

Hjt · Postby **Hjt** » Fri Sep 07, 2012 12:15 am

I agree with Hellmuns comments, I have 225/50 r15 Kumhos and they fill up the entire space, the difference to a 45 profile would suit my application, perhaps in the new set

I also wanted to add, the more grip your laying down the more you will transfer to your pads, rotors etc.

You will increase other areas of wear and tear. More strain on the drivetrain also.

mazmad · Postby **mazmad** » Fri Sep 07, 2012 7:13 am

Hellmum / HJT perfect, that's the info I was after. Noted re the extra stress through the braking / suspension, let alone fitting the 225s in the corner.

Good pads fluid - check. Right now my priority is focusing on where the biggest gains can come from - the gumby behind the wheel. But I am planning ahead for what comes next ...assuming the driver starts getting his act together

I will put 205's on the 8" wheels (as per nitrodanns input).

sailaholic · Postby **sailaholic** » Fri Sep 07, 2012 11:35 am

Hellmun, I was looking at a set of nittos on the weekend and they have usa, euro, and aus road approval on the sidewall.

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Hellmun · Postby **Hellmun** » Sat Sep 08, 2012 3:49 am

That would be a pleasant surprise if they're road legal here now but they were missing one of the symbols/dots last year when I checked. I'll have a look through my email archive and see if I can find what it was.