Which tire width to choose for stock wheels

[waldo22]

I have a California Route 1 RWD with the stock 18" x 7 wheels. I'm not looking to replace the wheels, but to get the best safety, handling, comfort and range from the wheels I already have.

I've settled on the Continental CrossContact LX 25 all seasons because they are highly rated on TireRack for almost every measure, are LRR, and are pretty universally praised.

It looks like the widest tire the stock wheels can support is 255mm.

Which setup makes the most sense?
235/60R18 103H square - 103 is the minimum acceptable load capacity, and are $30 cheaper each than XL
235/60R18 107V square - 107 XL may be overkill if 103 is acceptable?
235/60R18 107V front, 255/55R18 109H rear - both XL, staggered, this is the same setup as my VW ID.4
235/60R18 103H front, 255/55R18 109H rear - staggered, but with only 103 load in front? seems unwise to have such an imbalance.

My instinct is to go with a higher load capacity. What are the downsides to that, other than cost? Are the XLs heavier, worse range, etc.?

235/60 is about 0.5" larger diameter than stock at 29.1 vs. 28.6 stock, a 1.75% difference.
255/55 is about 0.4" larger diameter than stock at 29.0 vs 28.6 stock, a 1.4% difference.

Thoughts?

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[azerik]

255's would be a bear to jam on those 7 inch wheels, they'd also have a doughnut profile. The wider you go the more rolling resistance you add which means a drop in range. 235's are a good fit in my humble opinion.

 

[ebeponyan]

Even in the frequent rain and occasional snow of the PNW, I never had a problem with the stock Primacy Tour A/S. Unfortunately, some road debris did have a problem with them and we had to replace the whole set last year. We opted for the CrossContact LX-25s, and they've been solid. Should note that we have 19" Premium wheels, so the actual spec was 235/55 R19 105V XL for us, but the rim width is the same as yours at 7".

Yurt for scale.

It's hard to be quantitative on anything but price and lifespan mileage, which were both considerably better than the OEM Michelins. If I had to, I'd rate the Continentals as a barely perceptible upgrade in handling and aesthetics, and an equally barely perceptible downgrade in road noise and range. Ride comfort is a wash.

If you're looking for All Season tires to replace stock Summer tires for better handling in the elements, these are a good all-around pick. There is not enough differentiation from the stock All Season tires to justify the cost of a swap, in my opinion, unless your current set is damaged or worn down to end of life.

Edit: To echo the post above me, 235s look natural if a little more robust than stock, 245s are going to noticeably bulge out, which is a matter of stylistic choice, but starts looking silly to me. As you approach and surpass 255s, you will be muffin topping the hell out of your wheels and may even start interfering with the suspension.

 

[Auto Motive]

I have a California Route 1 RWD with the stock 18" x 7 wheels. I'm not looking to replace the wheels, but to get the best safety, handling, comfort and range from the wheels I already have.

I've settled on the Continental CrossContact LX 25 all seasons because they are highly rated on TireRack for almost every measure, are LRR, and are pretty universally praised.

It looks like the widest tire the stock wheels can support is 255mm.

Which setup makes the most sense?
235/60R18 103H square - 103 is the minimum acceptable load capacity, and are $30 cheaper each than XL
235/60R18 107V square - 107 XL may be overkill if 103 is acceptable?
235/60R18 107V front, 255/55R18 109H rear - both XL, staggered, this is the same setup as my VW ID.4
235/60R18 103H front, 255/55R18 109H rear - staggered, but with only 103 load in front? seems unwise to have such an imbalance.

My instinct is to go with a higher load capacity. What are the downsides to that, other than cost? Are the XLs heavier, worse range, etc.?

235/60 is about 0.5" larger diameter than stock at 29.1 vs. 28.6 stock, a 1.75% difference.
255/55 is about 0.4" larger diameter than stock at 29.0 vs 28.6 stock, a 1.4% difference.

Thoughts?

If range isn't an issue get the largest wheel andcctires that fit. We havecca GTPE with stock size Michelin pilot sport as4 all season xl that have been as advertised good in all weather conditions, added range, very quiet and at 14000 miles doing quite well on tread wear. Range is important and so far winter 220 to 240 and summer 270 to 285. 2.5kwh to 3.5kwh winter to summer avg. Good luck on tieee buy.

 

[waldo22]

Thanks for the tips! I should say that I am not "upgrading" my tires for the heck of it; my stock Michelin Primacy A/S still cover Lincoln's hair by 1mm or a bit more in the center of the tread, but the edges on all 4 are nearly bald at just under 18,000 miles, and there is some noticeable slippage in wet conditions.

What do you think of the 103 vs 107 load capacity for the 235s?

 

[tuminatr]

Sounds to me like your issue is you want a tire with better grip and note that the stock Michelin is not great in the wet. Grip especially in wet is all about the tread compound not the size. I would stay with the stock size if possible. Read some of the testing and find something that has tested to offer better wet grip.

Keep in mind if you change sizes is load range. For the tread patch to be flat on the ground it needs to support a certain weight. Car manufactures use the load range to calculate this and you can do the same.

If you put a 235/60/18 107 on the car you need to lower the tire pressure to 32psi. this would soften the ride a bid but could negatively effect range. If you inflate to stock 39psi the tire will be overinflated and wear out the center. I attached a chart

One other thought is XL load range is also referred to as reinforced, XL tires are designed to handle top heavy taller vehicles so even tough you may have the right load range in a SL you should not install a SL tire on the MME.

I also have a 225/60/18 and CR1 wheels on my premium. Because of the climate here in MN I went with a Vredestein Quatrac Pro and it's night and day wet performance it also is considerably better in snow. It did cost me some range but for me it's worth it for better grip and more precise steering better handling.

 

[RMoore]

Sounds to me like your issue is you want a tire with better grip and note that the stock Michelin is not great in the wet. Grip especially in wet is all about the tread compound not the size. I would stay with the stock size if possible. Read some of the testing and find something that has tested to offer better wet grip.

Keep in mind if you change sizes is load range. For the tread patch to be flat on the ground it needs to support a certain weight. Car manufactures use the load range to calculate this and you can do the same.

If you put a 235/60/18 107 on the car you need to lower the tire pressure to 32psi. this would soften the ride a bid but could negatively effect range. If you inflate to stock 39psi the tire will be overinflated and wear out the center. I attached a chart

One other thought is XL load range is also referred to as reinforced, XL tires are designed to handle top heavy taller vehicles so even tough you may have the right load range in a SL you should not install a SL tire on the MME.

I also have a 225/60/18 and CR1 wheels on my premium. Because of the climate here in MN I went with a Vredestein Quatrac Pro and it's night and day wet performance it also is considerably better in snow. It did cost me some range but for me it's worth it for better grip and more precise steering better handling.

I was wondering if you could explain what the numbers in the chart mean. I can’t figure out how to interpret the chart.

 

[waldo22]

The numbers are weight per tire, so multiply by 4 and that should be the total weight of the vehicle loaded. Vehicle curb weight PLUS load. That means you adjust your tire pressures based on the load you're carrying.

In practice, you keep it the same unless you've got it full of something heavy or are towing.

 

[tuminatr]

I was wondering if you could explain what the numbers in the chart mean. I can’t figure out how to interpret the chart.

Sure, that's what's called a load and inflation table. Essentially is shows how much weight a tire can carry at a specific inflation pressure.

In the case of the MME Ford picked between 1819 lbs and 1874lbs. A engineer will look a at the chart and see with a load range 104 tire he needs to inflate to 39psi. With a load range 104 tire inflated to 39psi the tread will ride flat on the road.

When changing tire size we can do the same thing. So if you go to a 235/60/18 107 it will support 1885lbs at 32psi. So because that tire has a higher load range it needs less pressure to support the same weight and have that optimal flat on the road contact patch. If you put 39psi in a 107 load range tire it would support 2149lbs, be overinflated and wear out the center of the tread

That's how the chart is used

Also why you see ford pick certain sizes

225/60/18 104 XL
225/55/19 103 XL
245/45/20 103 XL

Those three sizes are essentially the same height keeping things like ABS, traction controle, speedometers accurate

 

[waldo22]

After reading suggestions here and other places, I've decided to go with a square setup with 235/60R18 XL all around. Thanks @tuminatr for the advice that the XL reinforcement is important, and different than just the load rating.

235/60R18 is only .5" larger diameter than the stock 225/60R18, a difference of only 1.7%.

255/55R18 is the same diameter as 235/60R18, and definitely within the manufacturer's spec for the Continental LX25 on a 7" rim, just barely, but for every 4 people that say "I run 255s on my 7" rims and they look badass" or "they fit ok, I've never had any issues" or "they look fine", there is a seemingly more knowledgeable person who says:

255/60R15's are good for looks and straight line driving on a 7" rear wheel. They are terrible for corner handling. I have the 255's on the rear and the sidewalls flex or bounce from side to side a lot. I can give the car a shove on the side and watch the rear wiggle sideways for awhile.

and

While you can cram a 255/60 on a 7" wheel, it's not a great plan.
The sidewall just isn't supported properly and especially with such a tall tire will tend to do very odd things when stressed (like braking. turning, accelerating hard).

and

i wouldn't run anything wider than a 235 on a 7 inch rim. it looks like a balloon around the wheel and won't handle very well with that much sidewall buldge.

and

Its pretty pointless to put a 255 on 7.5 wheel. It'll look like a bubble and the tires' edges wont be making contact with the asphalt.

245 would be a little better. but 235 is ideal. I have 245s on an 8" and the sidewall looks pretty round. 235 sits very "square" on an 8" wheel. On a 7.5", 235 would look like my 245s.

They will "physically" fit. They'll just look funny, and not all of the tire's surface will meet the road...

I trust the folks talking about safety and handling more than the ones talking about how cool it looks.

In addition, according to the site Tire Scamp* (rim width/tire size chart near bottom) a 255 tire should be 75 or 80 series in order to avoid over-deforming the sidewall on a 7" rim. (ie. 255/75 or 255/80) Even a 245 should be 60 series or higher.

245/55R18 is stock diameter for the MME, but it doesn't come in XL, and 245/60R18 is a full inch too tall, 3.5%, but fits according to the chart.

Based on all that, it seems most prudent to stick with 235/60R18 XL on a 7" wheel.

*j/k it's Tires Camp. Not sure how reliable it is as a source, but it seems reasonable

 

[tuminatr]

Remember to run them at 32psi too. Otherwise they will wear out quickly

 

[DomMachE]

I have the select stock 18” wheels. I want to buy the pilot sport as 4 tires but it only comes in size 235/55/18 instead of the stock size of 225/60/18.

Any concerns if I install tires at that size? It would be slightly shorter with 55 height instead of 60.

 

[waldo22]

That's a small enough difference that it should be fine, but I'd rather go up 1/2" to 235/60 than down 1/2" to 235/55.

 

[Triggerhappy007]

I have the select stock 18” wheels. I want to buy the pilot sport as 4 tires but it only comes in size 235/55/18 instead of the stock size of 225/60/18.

Any concerns if I install tires at that size? It would be slightly shorter with 55 height instead of 60.

That's fine, I'd rather go with less sidewall since the 18" tires seem a little big. The good thing is that your speedometer will almost be exact now. When I set my cruise at 70, my GPS says 71 on stock tires.

 

[tuminatr]

That's fine, I'd rather go with less sidewall since the 18" tires seem a little big. The good thing is that your speedometer will almost be exact now. When I set my cruise at 70, my GPS says 71 on stock tires.

I think the speedo in the MME is GPS

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