Widest Tire?

lgilbert50@yahoo.com · January 13th, 2006, 4:22 pm

Wondering what the widest tire (thread width) that will fit on the MX3? Did a search but did not came up with anything?
Thanks
Lowell

Legato626 · Post by **Legato626** » January 13th, 2006, 5:30 pm

I got 205/40/17 on my car and when i turn my wheel i got a good 2in atlest on either side.

jschrauwen · Post by **jschrauwen** » January 13th, 2006, 5:36 pm

I think 215's are about the biggest else you may encounter rubbing on the spring platter.

tatsu · Post by **tatsu** » January 13th, 2006, 7:13 pm

225/45R-16's will fit with the correct offset. Vaughn Nishimura used to run them on MOMO Arrows (35mm offset, I think) until he switched to 17's. Not much tire selection in that size, though...

lakersfan1 · Post by **lakersfan1** » January 13th, 2006, 10:29 pm

I asked this question a year or two ago. The answer was 225.

rmcg5 · Post by **rmcg5** » January 13th, 2006, 11:54 pm

there are a few wheel spacers on ebay if you can't find rims with the correct offset....

PATDIESEL · Post by **PATDIESEL** » January 14th, 2006, 12:31 pm

On the stock offset the most you can run is 215 on a 7 inch wide wheel (mine rub just a tad at 215 40) If you use a different offset you can get a wider tire, but that is not always the best idea. You spread the weight over a larger distance and then will have less wieght on a given space of the tire. At a point it becomes too little friction to hold you to the road. Wider tires are only good for drag racing. Also getting an offset other than stock (42mm if I rememeber correctly) will wear out the bearings more quickly as the 42mm sits the wheel center of the bearing.

tatsu · Post by **tatsu** » January 14th, 2006, 3:22 pm

Stock offset is 45mm. The closest you can get in a 7" wide aftermarket wheel is 42 or 43mm, which some Enkei's and a couple of other Japanese-made wheels have, but those will almost certainly rub with a 215mm wide tire. Most of the common fitments for our cars use either 38mm, 37mm or 35mm offset. For the record, if I recall correctly the MOMO Arrows (the wheels that Vaughn was running 225/45R-16's on) had a 35mm offset.

What are the implications of changing your wheel offset? Well, aside from the obvious physical relocation, giving more clearance between the wheel and the suspension components and less clearance between the wheel and the fender lip, there are a few other changes.

First, you may notice an increase in torque steer because the driven wheels have more leverage due to being further outboard from the kingpin. Second, you may notice the steering being "quicker" or more responsive (or in some cases more nervous) because the wheel describes a larger arc around the kingpin. Third, you may not notice, but your suspension will be loaded at different angles than stock, so your ride quality may change, and the wear on other suspension components may increase. Fourth, because of the different loading, your wheel alignment may change slightly, increasing tire wear - get an alignment done!

Under most circumstances, you will want to keep your wheel offset as close to stock as possible. If you've ever tried to fit your finger in between the inside top edge of your rear tire and the strut housing on your MX-3, you know how little room there is in back! I can't even FIT my finger in between the strut and the tire at that point, and the tires I am running (Fuzion ZRi's) have a fairly rounded shoulder profile. With even a 215mm wide tire on the stock wheels with their 45mm offset, I have no doubt that the tire would rub on the strut under hard cornering. In order to go with any wider tires, a change in offset is necessary at the rear, either by using spacers or by changing to wheels with less positive offset.

If you want to go with 215's, you will need an offset of no more than +40mm, and that's not even taking a wider wheel into account. Bear in mind that when you go with a wider wheel, the tire will tend to "square-off" a bit more at the shoulder as well, so it is not surprising that the recommended fitments for our cars from the major wheel manufacturers (like OZ or BBS) are mostly in the +37 or +38mm range. For 225's, you will need a +35mm offset.

The idea that a wider tire will "spread the weight over a larger distance and then will have less wieght on a given space of the tire" is a common misconception, and is incorrect.

If you are using the same tire pressure and the same, correct diameter wheel/tire combo, the only thing that changes with a wider tire is the shape of the contact patch - the size of the contact patch stays the same. With a wider tire the contact patch is shorter and wider, and conversely a narrower tire will have a longer and narrower contact patch. At 28 psi tire pressure, your total tire tread in contact with the road on a 2500 lb. car is going to be around 89-1/4 square inches (give or take a bit for the tread pattern), whether those tires are 205mm wide or 225mm wide. All other things being equal, the wider tire's wider contact patch allows it to better prevent side loads from breaking its contact with the road.

lgilbert50@yahoo.com · January 18th, 2006, 2:59 pm

Just a note to thank everyone who replied, decided to keep the stock rims and use 215 tires. A note of interest tryed a friend's 245/50-16 tire and rim with 30mm offset and it cleared the suspension but you might have to bend the fender lip in to clear especially if the car is lowered.
Thanks
Lowell

Yoda · Post by **Yoda** » January 28th, 2006, 9:50 am

tatsu wrote:225/45R-16's will fit with the correct offset. Vaughn Nishimura used to run them on MOMO Arrows (35mm offset, I think) until he switched to 17's. Not much tire selection in that size, though...

I have a set of wide body front replacement fender in my collection of parts that would allow the uses of a 11" race slick on the car but it is pretty much pointless on a street car. The wide tire I have personally tried is a 235/35-18 which is pretty much useless. For the gross weight of the MX-3 once you get over a 215 the ground pressure becomes so light over the contact patch of the tire that you start to loose traction rather that gain. Even with the best rain tire there isn't enough pressure over the tire to press the tread through the water in many cases when you go to wide. The other problem is that it takes much more HP just to turn the wheel and tire combo just to over come inertia at a given rpm. On a dyno it is not unusual to see an increase of 10-14 hp at the wheels going from 17's down to 15's even though they weight exactly the same. On my car with a KL DE with -01 cams I went from 144whp to 156whp to 161whp by just swapping to smaller and/or lighter tire wheel combos.

PATDIESEL · Post by **PATDIESEL** » January 29th, 2006, 4:45 am

Ok, so correct me if I'm wrong, but didn't Yoda just confirm what I said about wider tires spreding the weight of the car differently.

I've heard both stories about tire widths and it is a good debate at the track. But I honestly think that in my experience a 215 worked better than a 225.
However, Tatsu's info seems well put together and is exactly what I've heard before. I think it comes down to a matter of preference for novices like us. It also doesn't make a lick of difference since none of us are pro race drivers and our ability is very much less than the cars handeling ability. I've proven that to myself time and again. (woo, watch Patrick do donuts in the runoff

)

tatsu · Post by **tatsu** » January 30th, 2006, 2:41 pm

The reason that wider tires hydroplane more easily is because of the hydrodynamics of their shorter and wider contact patch.

The wider contact patch has more frontal area, so its leading edge has to displace more water to reach the ground. On top of this, for the rest of the contact patch to be able to reach the ground, that water must be displaced faster because there is basically less "opportunity" for traction along its path for any given bit of road.

Conversely, a narrower tire, with its longer/narrower contact patch will both cut through the layer of water more easily because of its narrower frontal area, and will have more opporunity for traction because each bit of road is potentially in contact with the tire for a longer period of time.

Nd4SpdSe · Post by **Nd4SpdSe** » January 30th, 2006, 3:00 pm

tatsu wrote:The reason that wider tires hydroplane more easily is because of the hydrodynamics of their shorter and wider contact patch.

The wider contact patch has more frontal area, so its leading edge has to displace more water to reach the ground. On top of this, for the rest of the contact patch to be able to reach the ground, that water must be displaced faster because there is basically less "opportunity" for traction along its path for any given bit of road.

Conversely, a narrower tire, with its longer/narrower contact patch will both cut through the layer of water more easily because of its narrower frontal area, and will have more opporunity for traction because each bit of road is potentially in contact with the tire for a longer period of time.

Like snow tires. I remember seeing a advertisement cartoon about snow tires, about how wide tires act like snow shoes, spreading the weight. Ideally you want a narrower contact patch so sink through the snow to get the traction on the pavement

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