I want to know what's the largest tire size that I can go to, without rubbing or bottoming, under the following conditions:
- 7x17 Rims;
- 1.6" drop front and rear.

I previously run Hankook Ventus 205x40x17's (dia. 596mm/23.46").
(Original tire size was 195x65x14 (dia. 609mm/23.98")).
I'm more interested in increasing the profile.
I'm looking at:
- 205x45x17 (dia. +6mm/0.28")
- 215x45x17 (dia. +16mm/0.64")
- 225x45x17 (dia. +25mm/0.99").

So, ultimately the question is:
Can I go to 225 on a 7" rim with a 45 profile w/o rubbing?

10 people viewed yet no reply.
Is that perhaps because noone has done this or knows?????

I have since found out that a shop states that if you change the diameter of your tires then their recommendation is +/- 2.5%.

So, on that calculation, 215x45x17 should be OK (+2.6%).

Oh yer, that is a change from the standard tire size and does not take into consideration a drop.

So, does anyone know?

Other things to consider: odometer and speedometer being off.

Check out:
http://www.miata.net/garage/tirecalc.html

bottoming depends on how good your suspension is. Check out previous posts talking about springs and coilovers and other member's experiences with them.
>>

Thanks for the link claudio.
Yes you're absolutley right about the speedo reading.
But I reckon that if I can keep within a +/- 10% speedo reading I'll be OK.

I believe that increasing the overall tire size will mean I loose some acceleration but I'm not too worried about that as with the other mods I'm doing they will compensate for that.

What I am actually trying to do is close the gap between the tire and the wheel arch.
I am proposing to do this by lowering the susepnsion and increasing the tire size.
I have bought a set of new KYB GR-2's and some B+G lowering springs (1.6" drop all round).
I also have a set of TSW R Evo 7x17 rims.
So it just a case of figuring out what the max. tire size is that I can go for with a 1.6" drop.

Infact I have my answer in another thread '18" rims'.

I reckon I'll go for 225x45x17.
This will give me an overall drop of 2.6" all round.

Hey with 45 series profie tires your speedo wont be off that much. As with the width i duno if 225's will rub but 215s wont. Hope that this helps.
Bryan

Yer Bryan, that's my main concern.
If I go to 225 + with the 1.6" drop will the tire clear the wheel arch.
Especially under heavy cornering, braking, ...

I know that you can go to 225x45x16 but it's that extra 1".

I'd prefer to go for 225x45x17 but my safest bet would be 215x45x17.

I just want to be absolutely sure before spending out c$800 on tires.
(That's for 225x45x17 Michelin Sport tires, they're c$200 a tire here, then there's valves, balancing, fitting,...).

This post has been edited by vphmc: Feb 14, 2003 - 5:45 AM

I tried to do some research on this but im still a bit confused about tire dimensions. What does 225x40x17 mean? 225 is width or something i guess the 40 i dont know and the 17 is the wheel size. If someone could explain the dimensions a bit better and what is the widest tires i can get? I want plenty of grip so 17" Konig Verdict are fine but i dont know if 7.5 or 8 inch wheel widths will fit and how wide i can have the tires? Any help would be great, thanks guys. I also have dropzone coilovers I haven't yet install and they go from 0"-4" drop apparently and ill do maybe 2" when i add rims.

225x40x17 translates to:
225 is the width of the tire,
40 is the profile of the tire,
17 is the wheel diameter.

BTW: The site Claudio mentioned earlier is really good.