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I was wondering how many kilos above the stockos will i start noticing something different

What happens if my wheels are slightly heavier

Say if i go from my (NB8A Stock weight) 13.1lb = 5.9kg to 7.6kg
15x6 to 15x6.5 Offset 38mm

or to 8.2kg 16x7 Offset 42mm

Will I notice anything different and will going up a size change anything?

When I had a go in Zawrillas car way back when... Late model NA... it had huge rims on it that looked heavy as hell (I think he said they were heavy as hell too)... but when I got behind the wheel I didn't notice a thing... the power steering seems to mask the effect of them (the effect of feeling heavier at least)

As for numbers... Track guys would probably be able to give more useful information?

yeah

well i can't understand how it would make any difference except for the car weighing more overall

so i thought i'd ask before i go out and order these rims

Its certainly going to upset the spring/damping rates, which are usually worked out including the weight of the wheels. E.g. going over a bumpy section of road, the suspension movement wil tend to travel too far/react too slowly with a heavy wheel tyre combo, resulting in worse ride/handling. I noticed an immediate improvement switching from heavy Mazda upgrade 16 inch rims (9.5kg from memory), to 6.5kg 16 inch BSA rims on my NB8A.

increasing un sprung weight is one of the worst things you can do to a small car. much like the above comment handling will be worst - especially if you keep stock suspension that was designed and setup for the oem rims.

You'll also find that you need to flare the revs and slip the clutch more to move from a standstill, mine always feels soooooo much better when I put my 14's back on

Not only is the rim un-sprung weight the wheel is considred rotational mass. As it spins inertia takes place.

Personally if you gave me the choice I would rather lose 1 kg off a wheel than 4 kg of static weight off the body of a car.

Some belive that reducing the profile of the tyre, due to the larger rim also reduces the weight of the rubber slighly (less rubber in the side walls). And the reduced weight of the rubber is more imporant because its on the outer edge of the rotational mass. In theory it makes sence but no one has proven it to me in newton meters.

That would be similar reasoning as to why Autocrossers in the states have like... 13\" rims with 45 section tyres... I guess

I could always tell the difference between track rims and road rims.

Track rims did have semis on them though, but the weight difference was about 2kg/rims (with tyres on).

It was always so much easier to drive and steer with the road rims/rubber on.

Boags

DAM

I like the wheels but the weight got me concerned since people were talking about wheel weights

Anyway looks like I won't be getting them and leave it to the last option

Boags, You know those starcorp rims you have are they shiny? I don't like having a full wheel that is chromed I'd rather have just the lip but they say its shadow chrome but I\"m not sure how blinggy they are


What options do i have for rims around the $800 mark a full set (4 wheels) which are around the same weight as the stockos

I really notice the difference between my NB 15\" rims with 205/50 tyres and the standard 14\" 185/60 daisy wheels.

Acceleration is more sluggish with the 15\" wheels (greater rolling diameter and greater rotational inertia), plus worse ride quality.

The grip is much better with 15\" wheels, but that's likely to be the particular tyres fitted.

I don't think the MX-5 is all about grip anyway, it's the balance and feel. I much prefer the standard little skinny 185/60/14 wheel/tyres, the car dances around more and feels nimble.

Big wheels and tyres on an MX5 are like a ballerina wearing army boots!

well my plans are to keep the stock sizes

I wouldn't go above 6kg/rim unless they looked pretty damn good, and you have the power to spin them.

Chosen some wheels yet?

Oh about the comment on tyres having mass further out than wheels. I'm not so sure, since a bigger wheel doesn't move out the tyre anymore than it already is, it just takes up sidewall length, making them stiffer (good in some ways bad in others) and so moving the wheel out (the heaviest part of the wheel) to replace some little bit of tyre wall is going to move the mass out further than with smaller wheel and big sidewall.

But yes tyres do weigh heaps, they will at be more than the rim in some cases. Especially small rims with semi slick tyres (stiff heavy construction). My tyres weight more than the rim anyway, but they are incredibly light and handle brilliantly.

yup just this one


http://www.speedywheels.com.au/images/z ... silver.htm

I do hear the 17 brigade piping up once in a while about what all the hubbub is about with big rims, so each to their own really!
Just decide what your needs are... if it's possible borrow a set of rims from someone else for a test fit? See how you like them?