- My model of MX-5 is: Series 3
- I’m based near: Oxford
- I’m looking for technical help or recommendations on: Wheels / Tyres
Hi. Has anyone had any experience of running these tyres? I bought my MX5 in late summer last year and it was parked up in the garage during the winter so I haven’t done many miles in it. I drove it to Bath last weekend and it was horrible. It feels extremely nervous and wanders all over the place and when driving in a straight line on the motorway I was having to constantly correct the steering. It felt like it was imminently about to veer off the road at anything over 50. I wondered if it was down to this non-standard wheel / tyre combination which were fitted when I bought the car. The tyres are all good and the two rear tyres brand new. Should I go back to the standard wheels or is there something else in play here? I have booked it in to have the tracking checked next week.
They should be 205/45R17 on a mk3
What tyre pressures are you running ? - I use 28psi all round.
Also - I note you mention non std wheels
Do you know what offset ( ET ) the wheels are ? - if the offset is too much different to std it can feel twitchy.
If you have them available - I would try the standard wheels/tyres.
at least that would confirm or rule out the wheels/tyres causing the issue
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How OLD are the front tyres, and are they the same make and load rating as each other?
Do they have the same tread pattern and load rating as the rear tyres?
MX5s are very much happier with properly matching tyres all round.
Hi Richard. Many thanks for your interest. Both the front tyres are just a couple of years old. All the tyres are the same size, make and model. I bought the two rear ones to match the front.
I have owned a series 2 in the past which was a hoot and I loved. Wish I had never sold it. So I know how they should handle.
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Hi. I have stuck to the standard 29 psi in the absence of any other information. No idea what the offset is. I have included a picture for an indication. They don’t look wrong. The original wheels didn’t come with the car I would have to buy new or second hand.
“They should be 205/45R17 on a mk3”
Given that I have just bought two new tyres, will the 205/45 make a big difference? Will my speedo be over reading significantly?
Your picture looks like std 17" MX5 wheels so there should be no offset or fitment issues.
205/40R17 vs 205/45R17
Your car will now be going SLOWER for each indicated speed compared to the 45 profile.
I would start by swapping fronts to rear. (Ensure that any markings for ‘direction of rotation’ and ‘outside’ are showing correctly.
Then I think you need a full ‘spanner’ check by someone who knows what they are doing.
Finally a 4 wheel alignment check to see which way the tyres are pointing.
Out of interest, you haven’t said what brand of tyre you have.
Hi Mad_Malc. The tyres are all GT Radial SportActive 2 so I can’t see how that could be an issue. I think the first place to go in a 4 wheel alignment specialist. My guess is the front tyres are toeing out. We’ll see.
Anyone care to share with me what the values of a 4 wheel alignment for a series 3 should be?
If you have different makes of tyre on each axle then this will give the symptoms you have described. Also 40 series tyres will give a firmer ride.
The numbers I was given to set mine to were :
FRONT
Caster 5.0º
Camber 1.0º negative
Toe IN 0.15 Total ( .075 per side )
REAR
Camber 1.5º negative
Toe IN 0.15 Total ( .075 per side )
The wheel in your picture is the Mazda 17 inch wheel fitted to the Mk3 2L Sport so is not non-standard.
However it seems to be “kerbed” quite a bit.
Have you removed the wheels and checked for more serious wheel damage such as bent or damaged rims?
But definitely get an alignment check as well
I was having similar issues on my mk4. I was running standard 17 inch wheels with 205 /45 tyres. I’ve recently changed all four tyres to 215/45. it’s absolutely transformed the car. It’s so much softer feeling on the road and feels a lot less heavy on the steering. Yes, the speedo will be slightly out but not enough to make any real difference. Best mod I’ve done so far.
Hi Mr H. You are quite correct. I’ve just consulted the sticker on the inside of the door and the only tyre size it shows is 205/45R17. ■■■■■■! I was side swiped by the fact it had 205/40R17 fitted all round when I bought it. I’ve only just bought two more! Well, I’ll have to get at least a bit of wear out of them before I replace them again.
Nice to see they spelt ‘tyre’ corectly!
Hi George. With the shenanigans I’ve had with the wheels / tyres since I bought the car, when I come to replace them I think I will stick to standard. But thanks for the suggestion.
Definitely sounds like toe out issue to me. Around 0 deg on front toe should work well for you. Mine is set to 3 or 4 minutes (not degrees) toe in and it’s a wee bit too stable for me. Caster - as much as you can get with them matching and camber negative 1 to negative 1.5. Have rear set to 0.5 more neg camber than front.
I put eagle f1 asy6 from Costco all round at 205 45 17 and they are simply excellent.
