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MX-5 MK2.5 Wheel Offset


dswhite
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Hi,

 

I have a question I was hoping someone could answer:

 

I have a 2004 MX-5 Euphonic with 16" factory fit wheels. The wheels have seen one too many pot holes in their time and I'm planning to replace them with a new aftermarket set of wheels, and then get the car's geometry set up by the nice WIM guys.

 

The original wheels are 6.5" wide and have (I think) an offset of 40mm, whereas the new wheels I have my eyes on are 7" wide and have an offset of 35mm (they are still 16" diameter by the way).

 

Both the supplier and my own research agree that they will fit without any issue, but after reading the forums here I'm concerned that the different offset will upset the scrub radius and therefore the handling.

 

When I have the geometry setup is it possible to correct any errors in the scrub radius caused by the lower offset wheels?

 

Thanks in advance for any help,

 

David

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  • 1 month later...

Now that the original question has been answered, I can hopefully hijack this thread slightly...

 

Tony - you may remember I brought my old 350z to you a while back - Old thread.

 

I've just bought a Mk2.5 MX-5 Sport and I want to set it up for track and road. I'll hopefully squeeze in as many track days as possible but still want to use the Mazda on the road. I'll be my first car for learning how to drive on track and have fun so I want something that's set up to be enjoyable first rather than grippy as hell and faster than everyone else. Zero understeer with a smooth transition to easily catchable oversteer would be nice. :huh:

 

I'm going to replace the original 16" wheels with something smaller and lighter. Can you recommend the optimum size in your opinion? I don't think a 14" wheel will fit over the sport brakes (but correct me if you know differently), so I'm looking at 15" wheels, probably 6.5" wide with either 185/50 or 195/50 tyres.

 

What offset should I try to get? As mentioned previously in this thread, the Mazda wheels have a 40mm offset. In terms of handling, what would a 30mm offset do? At what offset would I need to start worrying about wheels touching the arches?

 

Thanks.

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For the OP, iirc, the Mark 1 5 has an offset of 45 on the standard Mazda wheels. No one I'm aware of manufactures wheels with that offset. Most replacement wheels, iirc are 37 offset.

Even though Mazda selected an offset of 45 for it's suspension set up, using a 37 offset apears not to affect the handling. (Especially if Tony has worked his magic on the car!)

Have you even had the car aligned before? It may be useful to go for the Mazda original settings, then once you're happy go for the fast road/track settings. No drawbacks on normal roads with these settings, but the full track settings, with a track shocks setup can be hard on the road! Fast road/track is a good compromise, great on track but not difficult to live with on a daily driver.

For Daave, you will get lots of different opinon on size, a lot of people use 15 for tyre choice, some 17's for looks.

I'd suggest asking that question on www.planetmx5.com or mx5nutz.com as there is a larger number of owners of the NB on those fora, especially those who track them.

h

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hms has more knowledge on this topic than me, his advice to ask forum members in planetmx5 is also wise since they are a collective force regarding the 5.

 

At the chassis the 5 is totally adjustable so i can make the car do whatever you like :lol:

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hms has more knowledge on this topic than me, his advice to ask forum members in planetmx5 is also wise since they are a collective force regarding the 5.

 

At the chassis the 5 is totally adjustable so i can make the car do whatever you like :(

 

Ok, following some advice on the club forums I've now bought a set of 15's and they're a lovely fit.

 

Next question relates to a full geo that I'm booked in to do on the morning of the 23rd... As the MX-5 is fully adjustable, is there scope to set the car up for fast road/track without any aftermarket bits required? The car will still be a road car but I hope to do as many trackdays as I can afford! Hence I'd like as little understeer as possible but with nice gentle progressive oversteer so I can learn how to corner properly (first track experience). If you strongly recommend some aftermarket adjustable bits what are they, how much £ and do you keep them in stock?

 

I fully intend to get some P5 Sportdrive suspension so that side of things will stay 'as is' for the moment.

 

Thanks.

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Once the car is lowered we can set the chassis pretty must out of the box. Once set i advise you feel where the car is lacking "if at all" then advance the chassis accordingly.

 

Blanket bombing the car with aftermarket goodies is fine for some but you could over modify the chassis and we have to "de-tune" the handling.

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Once the car is lowered we can set the chassis pretty must out of the box. Once set i advise you feel where the car is lacking "if at all" then advance the chassis accordingly.

 

Blanket bombing the car with aftermarket goodies is fine for some but you could over modify the chassis and we have to "de-tune" the handling.

 

So are you saying that a geometry check before the suspension gets changed isn't worth it?

 

I wasn't suggesting adding lots of aftermarket bits, but if there's something that everybody always changes then I'm interested to hear; otherwise I'm happier to leave it as-is as it's less expense. The main reason for me asking in advance is so that if there was a 'must have' item I knew what it was and could find out whether it was right for me before turning up and being forced to make a decision on the spot. :thumbsup_anim:

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Once the car is lowered we can set the chassis pretty must out of the box. Once set i advise you feel where the car is lacking "if at all" then advance the chassis accordingly.

 

Blanket bombing the car with aftermarket goodies is fine for some but you could over modify the chassis and we have to "de-tune" the handling.

 

So are you saying that a geometry check before the suspension gets changed isn't worth it?

 

I wasn't suggesting adding lots of aftermarket bits, but if there's something that everybody always changes then I'm interested to hear; otherwise I'm happier to leave it as-is as it's less expense. The main reason for me asking in advance is so that if there was a 'must have' item I knew what it was and could find out whether it was right for me before turning up and being forced to make a decision on the spot. :thumbsup_anim:

 

Changing the suspension then calibrating the chassis is a major mod, most add on's after this wouldn't need the chassis to be tuned again, like arb's or bracing.

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