tire size on a 18x8

[CHOSENMAN007 81]

What's the biggest tire size you can fit on a 18x8?

I'm running 225/40/18 yokohama v105s and they complement my abbey tuned car well. It tames the extra power but also let's the back end twitch when you go drivers aids half off.

Let's say I wanted more grip in the future when i go for more speed and ultimate grip but as a result less playfulness,what's the most I can fit on a 18x8 wheel. I was told a 235/40 will fit. What else?

[Lauren 2259]

Probably 235's. There is a tyre size calclulator you can google for. 

 

The trouble is if you fit too wide a tyre it won't feel good at all. 

[CHOSENMAN007 81]

Probably 235's. There is a tyre size calclulator you can google for.

The trouble is if you fit too wide a tyre it won't feel good at all.

You reckon 235 would be the limit Lauren?

[Lauren 2259]

Have a look on here James;

 

http://www.willtheyfit.com

 

245 may be the absolute limit, but check this link and see. 

[KevinA 695]

IMHO 245 is too big, if the sidewall gets too upright you can get deflection which could feel unpleasant.

[Lauren 2259]

Well, that the issue. 225's are the ideal size for the rim width. 

[DaveB 20]

Actually increasing the width of the tyre doesn't increase grip because the coefficient of friction will be the same. A bigger tyre will hold more energy before it overheats though. The best way is to change the compound to a more sticky type.

[DaveB 20]

What's the widest wheels you can fit to a gt86 anyway?

[KevinA 695]

Daveb depends on suspension, ride height and many other factors. Some prefer less unsprung weight while others more grip. Very subjective but interesting never the less. I run 18 x 9. 5 with no problems.

[CHOSENMAN007 81]

Have a look on here James;

http://www.willtheyfit.com

245 may be the absolute limit, but check this link and see.

Lauren that link is Amazing. Its say on a 235 I will lose 4mm to my arch and on 245 I'd lose 8mm. How I don't get it? I'm going wider no increasing the depth!. Am I missing something? Some one explain please.

[Special K 442]

James - 'tyre proflle' is a percentage of the width, not a fixed measurement..

 

Thus, a 245/45/17 profile will have a higher wall height than a 235/45/17 profile. 'Wall height' on a 245 dia tyre is 110.25mm - 'wall height' on a 235 profile tyre is 105.75mm

 

There's your 4.5mm...

 

Spec K

[DaveB 20]

[CHOSENMAN007 81]

Cheers k. So it would look like I'm lowered even further : ) Dave I'd like to see your vid 255s wow.

[DaveB 20]

Gt86 test: http://youtu.be/xhUcRkIBu0M

[CHOSENMAN007 81]

Looking at some Michelin cups! Views

[rob275 1817]

I imagine they will be similar to your pilot sports you had? Expect more road noise, but that's not particularly an issue I guess.

[Quixote 35]

Purely for track or track & road?

Great track tyre but not so sure about wear on the road...cup 2s maybe better, but I was warned off cups for my M3 purely because of tyre wear

Check with Ed re PSS on a car with SC...

[CHOSENMAN007 81]

Purely for track or track & road?

Great track tyre but not so sure about wear on the road...cup 2s maybe better, but I was warned off cups for my M3 purely because of tyre wear

Check with Ed re PSS on a car with SC...

How's your super sports going?

Yes if I got them id use them mostly on road and the rare track day. I think the cups are more usable than say r888s as they can actually hold up in the wet and considering I only use my car once a week it shouldnt be to bad. As for road noise the cars let I'm so much noise in themselves : )

Cup 2s cost a a great deal more.

Its a hard one out of super sports or cup 1s.

Only drama is my traction control comes on a lot and kills my fun! On hard driving of course so I need something more dry orientated. Or maybe Im just a heavy footer on corners lol

Quixote, did you use the cups daily?

[Lauren 2259]

You could turn the traction control and all that off. Way more fun in my experience!

[CHOSENMAN007 81]

Haha I did I almost turned round 90 degrees on a 4 way junction. : ) I'm trying to apply less throttle or feather it mid turn and awaiting the straight to floor it. But the corners is where I drop most people that try to race me. Hence the need for more rear traction. The Yoko's are awesome enough but the f.I puts a lot of pressure on them 1st and 2nd gear on tight corners. It will be good to see how everyone else with f.I copes with this. But then again I'm only on 225s.

[DaveB 20]

Soften rear suspension for better traction???

[Lauren 2259]

It's a difficult one because you don't want to over tyre the car. I've got the same tyres as you albeit on 17's, but I think this tyre has too much grip for an NA, as the rear doesn't come into play as much as it used to on the Primacys'. So Primacys are way more fun for me. 

 

I think you can put wider tyres on the rear as after all many have, but it means zero fun when it comes to getting it sideways. 

 

I also think you'll struggle with traction with any tyre in 1st gear. But if you are not interested in drifting the rear out of corners then wider tyres are realistically your only option. Also a bigger sidewall means less direct feel and more sidewall flex, it will make it harder to get sideways though as a result which is, I'm guessing what you want. 

 

Also as Dave points out, slackening off your rear dampers may help. 

[CHOSENMAN007 81]

It's a difficult one because you don't want to over tyre the car. I've got the same tyres as you albeit on 17's, but I think this tyre has too much grip for an NA, as the rear doesn't come into play as much as it used to on the Primacys'. So Primacys are way more fun for me.

I think you can put wider tyres on the rear as after all many have, but it means zero fun when it comes to getting it sideways.

I also think you'll struggle with traction with any tyre in 1st gear. But if you are not interested in drifting the rear out of corners then wider tyres are realistically your only option. Also a bigger sidewall means less direct feel and more sidewall flex, it will make it harder to get sideways though as a result which is, I'm guessing what you want.

Also as Dave points out, slackening off your rear dampers may help.

I'm fitting adjustable dampers this weekend which should help, no coil overs as I'm mainly a fast road guy. And coik overs are more for hard track in my view. Im thinking staying 225 on my 18s but just go to pilot super sports or pilot cups as they are more dry orientated.

Hard choice between the two tires. Just need to wear the Yoko's down ; )

[Lauren 2259]

Coil overs are not for 'hard track' (not sure what that is?). When it comes to suspension the more you pay the better it tends to be. Coilovers simply allow you a greater range of setup options and those could be towards track or indeed road settings. 

 

If you are using stock springs whilst adjustable dampers is not a bad move, i.e., it gives you an element of adjustment, so it may improve things for you. I guess you can try it and see. It sounds like to me, what you want is more grip in a straight line. It may be useful to speak with someone who's into drag racing and see what they do. 

 

The V105's are pretty sticky in the dry, too much for liking I admit, (though I quite like them in the wet) but given that I'm not sure the difference will be that apparent when switching to a similar tyre. 

[rob275 1817]

James anywhere on the road you can lose traction quite easily regardless of how your car is set up. Road surfaces have all sorts of bumps that can really unsettle a car, particularly if you catch one on a bend. You might not even notice or feel its there really. You could lower your pressures a psi or two. Of perhaps just control your foot...