M35 Tire Profiles

[chad bob]

I have a pretty general question about tires, currently my stag is running a set of 215 x 55 Bridgestones on the stock 7j 17" rims, the tires have quite a few screws stuck in them and they make a pretty crap noise when cornering . I have a full set of wet weather TOYO tires that were fitted to my track car, I think these will go really well on the stag. Problem is that the tires are 215 x 40 profile, I was wondering what affect going from 55 to 40 profile will have on my speedo?

Doable or not?

[[[d a n n y]]]

anything is doable

but i wont advise you to do it

speedo will read off badly

[scotty nm35]

Im running 235 45 17's and other than the speedo being out by 11% theres no problem.

[bbenny]

Yeah im running 215/55/17 and my speedo seems to be out 10%....

Ive just bought 19's, so i think ill go something like a 235/40/19 I think that was about the same size and see if I can get the speedo adjusted (is that possible?)

[180JDM]

I have 225/35/20 on my M35 and the speedo is 0.4% faster than stock

try this mate: http://www.miata.net/garage/tirecalc.html

[chad bob]

Thanks guys, so if i do this my wheels will be spinning 10.7% faster, so if my speedo says I'm doing 100Kph I'd actually be doing 89Km/hr not including the standard factory over read of about 7Kph.

Maybe I'll give it a miss, don't want to be the slowest thing on the highway!

[zei20l]

youd accelerate faster that normal tho

[pixel8r]

I find the standard speedo is out by nearly 8km at 100km/h already...wouldn't want to make it worse...

one thing to make sure is that the front and back tyres are all the same diameter & width etc. The AWD system does allow for a minimal difference (ie. to account for uneven tyre wear) but if the difference is too great it will play up.

[KiwiRS4T]

I'd put them on. Car will handle better. You just need to go by one of those displays at the side of the road that says how fast you are going and then you can calculate what your speedo should read to be doing 109km/hr on the motorway - there's no way you can pull max revs in top gear anyway so your real maximum speed will probably increase (or it would do if you didn't have the 180km/hr speed cut).

You can get a kit from Jaycar to correct your speedo if you need.

[chad bob]

one thing to make sure is that the front and back tyres are all the same diameter & width etc. The AWD system does allow for a minimal difference (ie. to account for uneven tyre wear) but if the difference is too great it will play up.

LOL my stag is RWD only bud. Keeps me bright eyed and bushy tailed on wet mornings

Cheers for the info Kiwi, might check out Jaycar.

[zei20l]

damn you kiwis and your ability to get ANY jap car!!!! lol

[Novaz]

might check out Jaycar.

Let me know how you get on with a Jaycar kit if you go that route, I'm keen to recalibrate my speedo also. It seems to read 6-7km/h under at 100km/h. It wouldn't be too bad, but the factory cruise control only goes up to 110km/h, which means 103km/h real, and that sucks

VQ25DD,RWD, RX, cruise, navi, HID, but only 16" wheels (wacky size too - 205-65-16)

[Paramour]

I have a pretty general question about tires, currently my stag is running a set of 215 x 55 Bridgestones on the stock 7j 17" rims, the tires have quite a few screws stuck in them and they make a pretty crap noise when cornering . I have a full set of wet weather TOYO tires that were fitted to my track car, I think these will go really well on the stag. Problem is that the tires are 215 x 40 profile, I was wondering what affect going from 55 to 40 profile will have on my speedo?

Doable or not?

http://www.1010tires.com/tiresizecalculator.asp

Just remember to keep it under or over 3% variance