Will 245/40/18 work?

As title says, I have a set of 245/40/18 winter tires laying around. Will they work on the stock rims and not rub?

 

Thanks!

is this for a 4th or 5th gen GT? If 5th gen on stock suspension it should fit no problem. Even with about an inch drop it should also work

1st 245 width winter tire isn't ideal for snow. The recommend rim width for that size is usually a minimum of 8", so the stock 18" x 7.5" rim is smaller than recommended size.

1st 245 width winter tire isn't ideal for snow.

 

Maybe off-topic, but I always heard this as well. Why exactly though? I know they say the narrower tires cut through snow easier, but here in NY you have to do that maybe 25% of the time. The rest of the time it is hard packed snow or ice where I would imagine more surface area the better....

 

typing this made me think of the random slush piles you plow through though.....

 

I ask because I see a lot of luxury cars still rolling on wide tires. Is it just a lack of knowledge/replicating OEM size, heavier vehicle, or something else?

is this for a 4th or 5th gen GT? If 5th gen on stock suspension it should fit no problem. Even with about an inch drop it should also work

 

Thank you sir. All i needed to know.

Maybe off-topic, but I always heard this as well. Why exactly though? I know they say the narrower tires cut through snow easier, but here in NY you have to do that maybe 25% of the time. The rest of the time it is hard packed snow or ice where I would imagine more surface area the better....

 

typing this made me think of the random slush piles you plow through though.....

 

I ask because I see a lot of luxury cars still rolling on wide tires. Is it just a lack of knowledge/replicating OEM size, heavier vehicle, or something else?

 

I could be wrong but I think you think of cutting as going through accumulated snow in the horizontal direction. On packed snow, the tire still needs to cutting vertically to the pavement.

 

Wider tires spreads the weight of the vehicle over a larger area. This reduce the weight per square inch of tire tread. A 245 is ~9% wider than 225, so it reduces the weight applied to a square inch of tread by 9%.

 

Snow tire work better if they penetrate deeper into the packed snow, so the aggressive snow tread can grip the packed snow or reach the pavement. Same goes snow over ice as you do not want to have a layer of snow on top of the ice.

 

The larger snow tires in general are made to fit larger OEM size wheels sizes.

"the tire still needs to cutting vertically to the pavement."

 

I know a lot of times this doesn't happen here as we will get inches of packed snow. It might bite in up to the actual tire, but often times the packed snow is still deeper than the tread is.

The bigger the surface area the more the snow/slush/water is under the tire. A smaller contact patch has more ability to squeeze the water and snow from beneath the tire and is less likely to ride up on top of the wetness (hydroplane).

I am running 245/40R18 on 18x8.5 rims with no issues right now but this is my summer set up. For my winter set up I have a narrow tire. I read through endless forums on what width of tires would do best in the winter. One thing that was noticeably absent in most of the arguments was what surface the car would be driven on. If you have any type of soft slush, snow, water, sleet, or similar cold weather precipitation on top of a hard road surface your best bet for traction is to cut down through that and get your tires on the road. This means heavy car, narrow tire, and winter rubber compounds with sipes to get traction on the pavement after you smash the snow out of the way.

 

If your goal is to float on top of the surface of soft materials because there is no hard road underneath it then yes you want maximum surface area. Somewhere there is a guy with an STI swapped Baja on quad tracks doing it right. For our cars where we have only about 1-2 sqft. in contact with the ground adding a couple extra square inches with a 245 tire won't make much difference (Baja boy is sporting something like 12-16 sqft of contact patch)

 

The only surface we haven't covered is solid ice or black ice (Why does it gotta be black ice?). In this case when you add or subtract surface area you are making slight changes to the overall surface area in contact with the road and maybe the psi in your tires but your car weighs the same. SurfaceArea x PSI = SupportedWeight. More Surface area means less PSI or if you have a wider tire with the same PSI it'll have a shorter, front to back, contact patch meaning the same surface area in theory. I tried to do all sorts of fancy math with various measurements and then I drove on an ice sheet covered parking lot. Unless you have ice spikes you aren't getting much for traction no matter how wide your tire is.

 

After all this I did a little thought experiment of how often I would be driving on the above surfaces. Most would be on cold dry pavement, next most would be soft ice surfaces, next would be the rare solid ice, and finally almost no off road. What ever tire size I have on cold dry pavement I will have enough traction for daily driving. For all the days of fresh snow, slush, and snow cone covered roads I need a narrower tire because it'll cut through better and get rubber on pavement. For ice if I lose traction I'm screwed so I will have to drive super slow no matter how wide my tires are because I'm not pulling over to put on chains or swap for ice spikes. Off road is last priority with this car but for the few times I might have to drive on a shoulder or turn around in an open field I think cutting down to the frozen dirt would be best.

 

This is just my general reading and research. I have not done any actual testing but if evidence says wider has a higher risk of hydro planing and does not increase contact patch in a meaningful way then the narrow winter tire is best. I am open to hearing other theories or conflicting research because I don't know everything.

A narrow tire will be better on packed snow as well, as you'll have more weight per unit area smashing the sipes into the snow, which, in turn, gives you better grip. There are probably cases where you'd want more surface area in the snow, but if you're driving on a road, a narrower tire is going to be better. If you're in an area that just leaves hardpack snow on the roads all winter, look into a set of studded tires, if those are street-legal in your area.