What's the diff 14" to 15" inch

Robbo107672 · Postby **Robbo107672** » Mon Jul 19, 2010 6:19 pm

G'day, let me get to the point quickly before I get a thousand different opinions..

My question has to do with sidewall length and handling at club sprint days... I'm looking for knowledgeable (less passionate) opinions on what the handling differences would be between say a Kuhmo 205/50/15 vs a Dunlop DZZ1 195/60/14 (I can't find a direct comparison within the one brand)..

There are obvious differences in compounds, tread width of 213 vs 202, diameter 587 vs 589 etc, and although these are important I want to take them out of the equation for now.

Will the difference for a 'rank amateur' to intermediate (hope to get there one day soon) sprint driver, be significant? I've heard people talk about how the tyres let go, quickly or more progressive etc, this is the type of stuff I'm looking for. I'm trying to decide if it's worth spending cash on wheels or should I just get good tyres on my 14" NA8 wheels..
(oh, btw, have an NA6 with minimal mods, springs, shocks, CAI etc, but not much more than that)

I appreciate anyone's time to respond !

Rob.

NMX516 · Postby **NMX516** » Mon Jul 19, 2010 7:56 pm

Just get good tyres on the NA8 rims. You're a 'rank amateur' so you won't notice a difference - you'll be much more focused on getting the car around the track than thinking about "what if" you had a different profile tyre. Larger wheels or lower profile tyres aren't going to make you go any faster, if that's your reason for asking the question. You'll make far greater gains towards improving your lap times if you just concentrate on your driving. The best way to improve lap times is to improve your skill behind the wheel.

A lower profile tyre will be more responsive.

manga_blue · Postby **manga_blue** » Mon Jul 19, 2010 8:43 pm

In a stockish NA8 you'd be quicker on 14s, providing you can find good tyres to fit. They're lighter than anything that doesn't cost megabucks, so the acceleration, braking and turn-in is generally better. The higher profile gives slightly better warning about grip.

Steampunk · Postby **Steampunk** » Mon Jul 19, 2010 8:52 pm

My first track day was on 185/50 R14 Bridgestone G-Grid III (now replaced by Adrenalin RE001) and I had a ball.

I wouldn't go for "gun" tyres straight off the bat because a "lesser" wheel & Tyre combination lowers your limit of adhesion which allows you to find out what the car will do when it's on the edge. Thusly it will teach you how to take smoother lines, how to correct oversteer/understeer, what happens when you lose traction under heavy braking etc.

If you go for really good wheels and tyres straight away, you'll be pedalling around corners way faster than your abilities may allow and you won't be ready for corrective action at higher speeds.

Guran · Postby **Guran** » Mon Jul 19, 2010 10:03 pm

If you want to be quick on the track, spend your money on trackday laps rather than tyres & wheels. Much more fun too! :mrgreen:

Robbo107672 · Postby **Robbo107672** » Mon Jul 19, 2010 10:24 pm

Thanks for the posts, good info and advise.

Rob.

Caffeine · Postby **Caffeine** » Tue Jul 20, 2010 12:46 pm

About this much >-----------------<

I did my first ~10 track days on the stock tyres that came with the car, and improved my times by 4 seconds, first track day to last. Even 14's will allow you to go round corners faster than you thought possible. No point in improving the car until you have found out the limits of what it can do now...