Car guys question about tire sizes [Archive] - Glock Talk

PDA

View Full Version : Car guys question about tire sizes


tslex
12-31-2012, 09:32
I need to replace the tires on my truck. I have what I acknowledge is a stupid question to anyone with more familiarity with this issue than I have -- which is likely everyone.

Current tire size is 285/70-17. Tires in this range can be awfully expensive.

Which of those parameters can I change in a new tire purchase? Any of them?

Obviously the rim diameter (17, right?) isn't changing without the wheel changing and I'm not changing the wheels.

I THINK I understand that 285 is tire width in mm. But is that the width at the rim (in which case I assume I cannot buy a different size) or the width measured somewhere else (in which case I assume I could use a different width)?

As for the the 70 -- I do not have any idea what that number means.

ETA: Maybe a simpler question: Can I replace the current 285/70-17 tire with a 265/70-18 tire on the existing wheel?

(I get it -- if you understand this stuff it sounds like asking if i can shoot .45ACP out of my 9mm. But I'm ignorant in this topic, so. . . _


Thanks in advance to the GT braintrust.

Glock30Eric
12-31-2012, 09:33
Tagged to get educated.

travisstorma
12-31-2012, 09:39
285 is the tire width at the tread. The 70 is the height as a percentage of the width.

285 mm with
285 x .7 = 199.5mm tall sidewalls on either side of the rim.
The 17 is the rim diameter.

Your overall tire size would be 285mm by 199.5mm + 199.5mm + 17 inches. This would be roughly 11.2 by 32.7 r 17 tire.

travisstorma
12-31-2012, 09:40
ETA: Maybe a simpler question: Can I replace the current 285/70-17 tire with a 265/70-18 tire on the existing wheel?




No. The 17 has to be the same.

Dan_ntx
12-31-2012, 09:40
Percentage of height to width.

285 = width in mm
70 = % of height to width (70% of 285mm tall)
17 = rim size

Remember that 25.4 mm= 1 inch when doing your calculation

Or use a tire size calculator on the interweb

MtBaldy
12-31-2012, 09:44
Not an expert but have gone through some of this looking for performance tires. The 285 is the TREAD width. The 70 is the aspect ratio. The 17 is as you surmised the wheel diameter. Usually if you change both aspect ratio and tread width you can come close to keeping the same wheel/tire diameter which means your speedometer will stay close. For instance if you go up a size in tread width you go down in size on aspect ratio. As an example only, if you go to 295 tread width you would go down to a 60 aspect ratio. Since the rubber is flexible and under pressure you have some flexibility with the rim. You need to know the rim width and how close your current tires are to it's maximum, or minimum, tire size your current tires are. Finally, my main source of information was here:

http://www.tirerack.com/FAQ/index.jsp

tslex
12-31-2012, 09:44
No. The 17 has to be the same.


Thanks. I see that. 17 is the diameter of the rim, so that's fixed. Got it. Does the 285 have to be the same? Because that seems to be the biggest effect on price point, all other things equal.

MtBaldy
12-31-2012, 09:45
Thanks. I see that. 17 is the diameter of the rim, so that's fixed. Got it. Does the 285 have to be the same? Because that seems to be the biggest effect on price point, all other things equal.

No, the tread width and aspect ratio are where you have some flexibility.

tslex
12-31-2012, 09:52
No, the tread width and aspect ratio are where you have some flexibility.


Baldy, thanks! That was my core question I guess, whether the diameter was the diameter at the rim or somewhere else (tread per your your response).

Cost difference can be $50/tire going from 285 to 265.

Truck spends 90 percent of its life on the pavement (but often in tons of rain), 7 percent on unpaved roads, and 3 percent off road, but mostly in fields and at the range.

I've learned over 135K miles that the best combination is a moderately aggressive tread, but with deep siping for all the rainy pavement I drive on.

Thanks to GT GNG for a quick response. Any general advice on tires also welcome.

NAS T MAG
12-31-2012, 09:53
This should help you. You have options.

http://www.tiresizecalculator.info/

skinny99
12-31-2012, 09:53
Depending on what kind of truck you have you could change the width 285 or the Aspect ratio 70. However if you want the tire to remain the same size it will be very tough to alter either. Even going slightly larger ups the price considerably. I would never go smaller, looks like crap and hurts fuel mileage and ride quality. 285/70-17 is a very popular tire and will be the cheapest way out.

One option you may try is craigslist or your local performance wheel and tire shop. Someone may be selling some low mileage "takeoffs". Lots of guys take off almost new tires and wheels to put bigger wheels and tires on. Of course the downside is no warranty on balance or trueness of the tire. Just a suggestion.

Dan_ntx
12-31-2012, 09:57
No, the tread width and aspect ratio are where you have some flexibility.

Just use a tire size calculator or manually calculate the total height and get close to what you have currently so you don't change your final drive ratio or make your speedometer inaccurate.

Another consideration is tire width to wheel width. If you make your tire too wide or too narrow for the rim you will have issues, however you can generally add or subtract 30mm of width with no impact...just make up for the total height by changing the aspect ratio.

Discount tire's website will suggest alternate sizes BTW, I'm sure others will too.

If you are looking for inexpensive tires, have you looked at Treadwright? Good quality retreads that are popular in the Jeep and off road community. I know lots of guys who run them trouble free on their Jeeps.

CitizenOfDreams
12-31-2012, 10:36
My 2 cents worth of tire advice: unless you really know what you are doing and what are you trying to achieve, it's probably best to stay with the factory recommended size and load rating.

If you are on a budget, there is some room to choose between more expensive and less expensive brands/models. But changing the tire size just to save money is most likely false economy.

wrczx3
12-31-2012, 10:41
The closest size I could figure out would be a 255/75/17. The would be 1/10 of an inch shorter and 30mm (1.18") narrower. I know nothing about guns but sold tires for 20 years.

itstime
12-31-2012, 10:45
285 is section width. Not tread width

I'M Glockamolie
12-31-2012, 10:50
What is the year, make, model of truck? Try tirerack.com to see if you have any better options in the stock size.

wrczx3
12-31-2012, 10:54
Don't forget to look at the load index and speed rating.

pipedreams
12-31-2012, 11:01
My 2 cents worth of tire advice: unless you really know what you are doing and what are you trying to achieve, it's probably best to stay with the factory recommended size and load rating.

If you are on a budget, there is some room to choose between more expensive and less expensive brands/models. But changing the tire size just to save money is most likely false economy.


This................

Your don't want to go with smaller than the factory originals. Lots of good brands other than what the factory puts on. When I put new tires on my truck someone suggested Kumo tires and I got a good price and they seem to be working out great after a year. Check around and I'm sure you will get some good recommendation here on the forum.

LEO/Dad
12-31-2012, 11:28
Many people don't realize that your vehicle's recommended tire size is on your door jam label along with recommended inflation pressure. If there were ever any liability issues, I would have to assume that this would be checked!

wrczx3
12-31-2012, 11:37
Many people don't realize that your vehicle's recommended tire size is on your door jam label along with recommended inflation pressure. If there were ever any liability issues, I would have to assume that this would be checked!

You are right. A lot of tire shops will not replace your tires with anything but the factory size. Any shops I have worked in will as long as the new tires are very close to stock size and the load index and speed rating are the same or higher on the replacement tires.

prism
12-31-2012, 11:38
you can shop online for tires at amazon and other sites

XshooterX
12-31-2012, 11:41
If your truck's suspension is stock, check the door jamb for proper tire size. If your current tires are different than that, use an online tire size calculator to see how much of a size difference there is. Then, decide whether you like the looks of current tire size or if you'd rather go to what the factory recommends (if there is a difference at all). Once you've decided on size, look to Craigslist to buy. I buy all of my tires there and have saved thousands.


Posted using Outdoor Hub Campfire (http://www.outdoorhub.com/mobile/)

janice6
12-31-2012, 11:42
Minor note:

Ask the "Rolling diameter" of the tire versus the same for your existing tire. It will determine what the speedometer error will be.

tslex
12-31-2012, 13:23
Thanks to all.

Very useful information. I learned a lot.

So at the end of the day, I think I end replacing with another set the same size. Good info about consequences of size changing.

Actually found these on the Walmart site. Similar to what's on there now, moderately aggressive, with the siping that helps a lot on rain covered roads here. I can replace the set for under $1000 -- which would be nice. I'll look around for independent reviews and other tires, but feel like I have a bot better idea what to look for.

http://www.walmart.com/ip/Nitto-200-990/19473702

tarpleyg
12-31-2012, 13:30
What's the warranty look like on your current set of tires? I ask only because I just had a set of Kumhos replaced and only paid 40% of the regular price I was quoted at two different shops. It's worth checking out.

tslex
12-31-2012, 13:55
What's the warranty look like on your current set of tires? I ask only because I just had a set of Kumhos replaced and only paid 40% of the regular price I was quoted at two different shops. It's worth checking out.

I'll check it out. But I've currently got Toyo tires on it. They have ~40K plus, and certainly still have some wear left in them. Problem is the tread is worn past where the siping was cut and that's really the key feature that makes the truck handle very well at high speed in the rain. (You remember that bit about life here, Greg - standing water on the roads 6 months a year.)

I cannot see that there is anything WRONG with the tires that would give rise to a warranty issue -- they are just worn. But certainly I'll ask.

My repair shop are the ones who put them on last time and I paid about $1000 for the tires. If I can save a couple hundred going elsewhere, I would. Although the big places -- Tire Kingdom etc -- all seem set up to rip you off.

ETA: I am probably over thinking this, but at 135K, I'm assuming this will be the last set of tires and they'll likely outlast the truck.

hogfish
12-31-2012, 15:26
Just wanted to mention that the the height in % of width has to be the most retarded, dum, stupid, backwards, hinky, commie trick ever pulled. :steamed:

:supergrin:

wrczx3
12-31-2012, 15:44
I'll check it out. But I've currently got Toyo tires on it. They have ~40K plus, and certainly still have some wear left in them. Problem is the tread is worn past where the siping was cut and that's really the key feature that makes the truck handle very well at high speed in the rain. (You remember that bit about life here, Greg - standing water on the roads 6 months a year.)

I cannot see that there is anything WRONG with the tires that would give rise to a warranty issue -- they are just worn. But certainly I'll ask.

My repair shop are the ones who put them on last time and I paid about $1000 for the tires. If I can save a couple hundred going elsewhere, I would. Although the big places -- Tire Kingdom etc -- all seem set up to rip you off.

ETA: I am probably over thinking this, but at 135K, I'm assuming this will be the last set of tires and they'll likely outlast the truck.

If you want tires with deep siping look at Michelin. They are the only one I know that use full tread depth siping.

Glock30Eric
12-31-2012, 15:49
Hey why don't you order tires at Tirerack.com something like that then have wal mart guys install it for you. You'll save 40% of $$ from doing that.

tarpleyg
12-31-2012, 16:07
I'll check it out. But I've currently got Toyo tires on it. They have ~40K plus, and certainly still have some wear left in them. Problem is the tread is worn past where the siping was cut and that's really the key feature that makes the truck handle very well at high speed in the rain. (You remember that bit about life here, Greg - standing water on the roads 6 months a year.)

I cannot see that there is anything WRONG with the tires that would give rise to a warranty issue -- they are just worn. But certainly I'll ask.

My repair shop are the ones who put them on last time and I paid about $1000 for the tires. If I can save a couple hundred going elsewhere, I would. Although the big places -- Tire Kingdom etc -- all seem set up to rip you off.

ETA: I am probably over thinking this, but at 135K, I'm assuming this will be the last set of tires and they'll likely outlast the truck.

Nothing has to be wrong with them. If you bought Toyo tires that had a 60K mile warranty and you only got 40K out of them, they'll prorate a new set for you. Lots of people forget about the warranty when they buy tires. My last set I referred to had a 60K mile warranty. I got ~30K out of them before they needed to be replaced. I went to a Kumho dealer and they replaced them for me at a deep discount.

tarpleyg
12-31-2012, 16:10
Oh, and I would never buy a truck that I couldn't confidently get 200K miles or more out of. If that Nissan won't last through this new set of tires, I'd not be buying another Nissan product. You should be able to get 250K no problem. I have a Chevy Colorado with 125K on it and I fully plan to give it to my daughter when she starts driving in 10 years. My dad has a Yukon with 1/4 million miles on it and it's still going strong.

tslex
12-31-2012, 19:26
Nothing has to be wrong with them. If you bought Toyo tires that had a 60K mile warranty and you only got 40K out of them, they'll prorate a new set for you. Lots of people forget about the warranty when they buy tires. My last set I referred to had a 60K mile warranty. I got ~30K out of them before they needed to be replaced. I went to a Kumho dealer and they replaced them for me at a deep discount.

Oh well nifty. For an educated man, I sure am dumb about tires. I will check it out.

tslex
12-31-2012, 19:30
Oh, and I would never buy a truck that I couldn't confidently get 200K miles or more out of. If that Nissan won't last through this new set of tires, I'd not be buying another Nissan product. You should be able to get 250K no problem. I have a Chevy Colorado with 125K on it and I fully plan to give it to my daughter when she starts driving in 10 years. My dad has a Yukon with 1/4 million miles on it and it's still going strong.

And I hear you. It's more the truth that I'm more interested in getting a new truck someday than actually needing a new one. This truck has been excellent, barring brake problems at the outset that were addressed under warranty.

I guess I'll likely GET 200K -- but sometimes I don't WANT to. Rode in a buddies newish Raptor the other day -- s@!t hot.

Wyoming
12-31-2012, 19:46
Just wanted to mention that the the height in % of width has to be the most retarded, dum, stupid, backwards, hinky, commie trick ever pulled. :steamed:

:supergrin:

You forgot the ply rating for tires! An 8 ply tire is equal a tire made with 8 layers of cotton fabric when tires were made with cotton for reinforcement. When they went to nylon they started the ply rating. Now with steel we still have the ply rating based on cotton.:dunno:

Now the height to width % seems logical.:rofl:

CitizenOfDreams
12-31-2012, 20:13
And on top of that, they still measure the rim diameter in inches. :faint:

Lunkerbass
12-31-2012, 20:20
Try Discount Tire Direct on line . They offer free shipping to your residence or drop ship to your preferred installer
If your looking to get the most longevity don't forget to get a high treadwear rating


Posted using Outdoor Hub Campfire (http://www.outdoorhub.com/mobile/)

ray9898
12-31-2012, 20:33
I always laugh at the tire size cluster.

Rim size in inches, width in mm, height in a funky percentage. There had to be an easier way.

JDennis
12-31-2012, 21:03
I will apologize up front if anything I say is repeated. Tire size is relative only to aspect ratio. The most important is rim size obviously. Rim width is very important cause you can only differentiate aspect ratio within a certain width of the rim. Most vehicles list a alternate tire size on their sticker in the jam. Rule of thumb is can only go up or down one size given the rim width completely safely. So if the tire is 235/70 and want to go up in size would be 245/65 or 225/75 if you want to go down in size. Sometimes manufacturers skip and going up in size would be something like 245/60 or vice versa depending on rim size to keep the same diameter. Fords and Nissans (I own both) are notorious for odd sizes. Just make sure the overall diameter is close which there are a zillion calculators online. For a good tire check out a destination le from firestone for a truck/suv. I am not a big firestone fan, but they are a great and reasonably priced tire.

CitizenOfDreams
12-31-2012, 21:14
I always laugh at the tire size cluster.

Rim size in inches, widthm in mm, height in a funky percentage.


And the bolt circle can be inches or millimeters. And so can the lug nuts/bolts themselves. :faint:

There had to be an easier way.

Yes, it's called "the metric system". You Americans should look into that. :wavey:

JDennis
12-31-2012, 21:19
Yes, it's called "the metric system". You Americans should look into that. :wavey:

Thanks! You seem to be "winning" that battle lol I used to only need to buy SAE.

CitizenOfDreams
12-31-2012, 21:30
Thanks! You seem to be "winning" that battle lol I used to only need to buy SAE.

Resistance is futile. You will be assimilated. http://t0.gstatic.com/images?q=tbn:ANd9GcTXbnxRHDL31sh5pN2hvkcc-U4BcDzQ1kdd2Uq5a6uB-KTrDPAxwJ8nWw

Seriously, can someone explain to me what is so attractive about the Imperial system? Weird fractions like 35/64th, 16 ounces in a pound, 5280 feet in a mile, water boiling at 212 degrees... :shocked:

JDennis
12-31-2012, 21:36
Resistance is futile. You will be assimilated. http://t0.gstatic.com/images?q=tbn:ANd9GcTXbnxRHDL31sh5pN2hvkcc-U4BcDzQ1kdd2Uq5a6uB-KTrDPAxwJ8nWw

Seriously, can someone explain to me what is so attractive about the Imperial system? Weird fractions like 35/64th, 16 ounces in a pound, 5280 feet in a mile, water boiling at 212 degrees... :shocked:

It seems that way. After all it seems 9mm, 7.62, and 5.56 is all the rage these days.

DanaT
12-31-2012, 23:00
Resistance is futile. You will be assimilated. http://t0.gstatic.com/images?q=tbn:ANd9GcTXbnxRHDL31sh5pN2hvkcc-U4BcDzQ1kdd2Uq5a6uB-KTrDPAxwJ8nWw

Seriously, can someone explain to me what is so attractive about the Imperial system? Weird fractions like 35/64th, 16 ounces in a pound, 5280 feet in a mile, water boiling at 212 degrees... :shocked:

One of the rumors (and the numbers bear it out for average temperature) is that the Fahrenheit scale has 100 degrees based upon a cows rectal temperature.

Now dont you think tire measurements are much more socially acceptable now?