1 2
Andy Hollis
Andy Hollis
3/29/23 8:43 a.m.

We hear it all the time: What’s the widest tire I can fit under my car? Bigger is always better, right? 

Not necessarily. From a performance standpoint, what matters more than tire width is optimal wheel width to support the chosen tire size. But don’t take our word for it. Let’s look at some data from our many years of …

Read the rest of the story

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
3/29/23 11:46 a.m.

So, run the widest wheel you can unless the rulebook says you can't? 

That's a great looking Flyin' Miata 17x9 Kogeki wheel ;)

Mndsm
Mndsm MegaDork
3/29/23 11:56 a.m.

I remember reading an article many moons ago in sport compact car. The car in question was the jun hyper lemon evo. It had a square TIRE setup, but the rear wheels were actually narrower. The front wheels were the width to give them the flattest tread face possible, at the expense of sudden breakaway at the limit. The rears where narrower, which put a bubble on the tread patch, for more progressive breakaway and ease of rotation of the rear end. It was fascinating stuff and something that's always stuck with me. 

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
3/29/23 12:07 p.m.

I specifically went for a narrower wheel for the Targa Newfoundland (225/45-15 on a 15x8) to get more sidewall compliance. Also gave me a lighter overall weight. But that was tuning for a rough surface and not purely for lap times. 

I tend to do the same on my street cars as well for the same reason. 

z31maniac
z31maniac MegaDork
3/29/23 12:13 p.m.

In reply to Keith Tanner :

That is a good looking wheel. Reminds me of the Titan 7.

jamesgeck
jamesgeck GRM+ Member
3/29/23 1:07 p.m.

I've been thinking about this. Currently have 315 Falken RT660s on 11" wheels. Could I be faster with RE71RSs in 295 30?

 

dean1484
dean1484 GRM+ Memberand MegaDork
3/29/23 2:42 p.m.

Our general approch was wider tire but smaller over all diameter at slow tight tracks. Taller narrower tires for high speed tracks. Sidewall night we tried to keep as constant as possible. 
 

One thing we use to measure was rolling resistance. Not scientific by any means but we had a small paved access road to our shop with a small hill leading to a quarter mile strait. We had a fixed starting point on the hill and just let the car roll. The further it went the less rolling resistance. I know alignment will impact this as will ride height but it made for a good comparison if you did a test with one set and then swap the tires and test again. Tests months or even weeks apart were not comparable. 

z31maniac
z31maniac MegaDork
3/29/23 3:26 p.m.
jamesgeck said:

I've been thinking about this. Currently have 315 Falken RT660s on 11" wheels. Could I be faster with RE71RSs in 295 30?

 

Just put the 315s on 12"s devil

Olemiss540
Olemiss540 HalfDork
3/29/23 3:30 p.m.

Absolutely without a doubt, surprised this is even a question. The more girth the better with anything wrapped in rubber. 

Andy Hollis
Andy Hollis
3/29/23 6:53 p.m.
Keith Tanner said:

I specifically went for a narrower wheel for the Targa Newfoundland (225/45-15 on a 15x8) to get more sidewall compliance. Also gave me a lighter overall weight. But that was tuning for a rough surface and not purely for lap times. 

I tend to do the same on my street cars as well for the same reason. 

Keith...the other way to get more sidewall compliance is to go -1 on diameter. While not typically an option for 15's, it certainly is for 17's and larger.  For example, an 18" wheel/tire package in front and a 17 in the rear...both with the same OD and width tires.  Same donut...different sized holes.

 

Andy Hollis
Andy Hollis
3/29/23 6:55 p.m.

As an aside...

Can anyone identify that grass in the lead photo?

Some very famous turf, right there.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
3/29/23 7:59 p.m.

In reply to Andy Hollis :

Yup, I recommend a -2 to most Mazdaspeed Miata owners. But it wasn't an option for me :) 

z31maniac
z31maniac MegaDork
3/29/23 9:48 p.m.
Andy Hollis said:

As an aside...

Can anyone identify that grass in the lead photo?

Some very famous turf, right there.

A cross of Kentucky Bluegrass, Featherbed Bent, and Northern California Sensemillia.

Andy Hollis
Andy Hollis
3/30/23 6:27 a.m.
z31maniac said:
Andy Hollis said:

As an aside...

Can anyone identify that grass in the lead photo?

Some very famous turf, right there.

A cross of Kentucky Bluegrass, Featherbed Bent, and Northern California Sensemillia.

laugh

You might be right on that last point...

It's the infield at Daytona.  Who knows what seeds have fallen there from fans.

Ando
Ando GRM+ Memberand New Reader
3/30/23 1:58 p.m.

In reply to z31maniac :

Cannonball!!

I'll just take a drop and play through here. 

VolvoHeretic
VolvoHeretic GRM+ Memberand Dork
3/30/23 7:18 p.m.

My car has 2" wider wheels than the treads. I am satisfied. I was worried 20 years later that these Weld Draglite wheels might not be strong enough for canyon carving so I called them up and they said as long as they were not race tires, I would be fine.

livinon2wheels
livinon2wheels GRM+ Memberand Reader
4/21/23 7:30 a.m.
Olemiss540 said:

Absolutely without a doubt, surprised this is even a question. The more girth the better with anything wrapped in rubber. 

now that is a quotable quote lol

Matthew Kennedy
Matthew Kennedy GRM+ Memberand HalfDork
6/27/23 8:34 p.m.

In reply to SlammedStanceSpeed :

Protip: if you take in the bare wheels and tires, they really don't care what you're putting it on.  They really only complain if you show up with a car and ask them to put something on that's far off the stock size.

Confusedtuning
Confusedtuning New Reader
7/14/23 8:03 a.m.

I'm running 245/40/17 square on 17x8 inch aftermarket wheels and wondered if I should buy 17x9 instead. 

The cars a 135i coupe with lots of modifications like powerflex black bushings and m3 controls arms but is setup to be a fast b-road daily driver car on potholed and tight English roads and never/almost never will be on a track pushing times or competing. 

I picked 17x8 inch originally because I thought less weight and better ability to cope with poor surface and such would yield better real world performance but after reading here and other places I can't help but wonder if I messed up? I wonder if someone would be able to advise. 

Confusedtuning said:

I'm running 245/40/17 square on 17x8 inch aftermarket wheels and wondered if I should buy 17x9 instead. 

The cars a 135i coupe with lots of modifications like powerflex black bushings and m3 controls arms but is setup to be a fast b-road daily driver car on potholed and tight English roads and never/almost never will be on a track pushing times or competing. 

I picked 17x8 inch originally because I thought less weight and better ability to cope with poor surface and such would yield better real world performance but after reading here and other places I can't help but wonder if I messed up? I wonder if someone would be able to advise. 

It sounds like you're on the right track (no pun intended, but, eh, I'll take it...).  Read Keith's post above re: Targa Newfoundland.

Confusedtuning
Confusedtuning New Reader
7/15/23 3:31 p.m.

In reply to ГУЛАГ мальчик УР следующий :

I had read that before posting and it gave me some hope I hadn't got it wrong. I suppose by posting I wanted to see some more opinions on this line of thinking as I'm unsure if I picked well. 

racerfink
racerfink UberDork
7/15/23 3:41 p.m.

I've heard that running too wide a tire won't generate enough heat in the tire sometimes.  Running a narrower tire might help generate optimal tire grip because the tire runs in it's intended heat range.

I know that when I worked for Joe Varde's Firestone Firehawk team, we ran 255's in the dry, and 225's in the wet.  That would be another instance where a narrower tire would be optimal.

Confusedtuning
Confusedtuning New Reader
7/15/23 6:28 p.m.

In reply to racerfink :

The threads more about wheel width for a given tyre width, so a 245 tyre on either an 8, 8 1/2 or 9 inch rim.

A narrower tyre vs wider tyre is different 

RX8driver
RX8driver Reader
7/16/23 10:29 a.m.

I've read that Goodwin Racing had found with RX8's that 255's were faster on straighter, faster tracks and 275's were faster on slower, twistier tracks (stock = 225). So yes, tire size optimization is also a factor.

Andy Hollis
Andy Hollis
7/16/23 6:46 p.m.
Confusedtuning said:

I'm running 245/40/17 square on 17x8 inch aftermarket wheels and wondered if I should buy 17x9 instead.

Only if you want the car to handle better and be faster on track. :)

That size tire is always quicker on a 9. 

But if its just for street use, the 8 will be more comfortable.

1 2

You'll need to log in to post.

Our Preferred Partners
YJSya5IAcpOuKPi9lvtaMfKpnsEiFoxgKCvBfVNPlX664rPXN9mbEXCKhi9y70Qp