Tire Size, Max. tire size for 7x17 / 1.6" drop? Options

[3TST]

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?

[3TST]

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%).

[3TST]

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

So, does anyone know?

[claudio]

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.

[3TST]

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.

[Cragspider]

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

[3TST]

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

[Milds3vn]

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.

[3TST]

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.