help with tire size please!!!

[PastorIke]

hey guys...I was just wondering if I could change out my stock P245 70 R16 tires on my 2002 Eddie Bauer Explorer for LT245 75 R16 tires? Is there much difference? Is that gonna throw my speedometer off any? I just am pretty ignorant to tires except I know I need all 4 new ones right now...any help would be appreciated!!!

 

[suzukigod308]

i think it might only have a little harder ride cause of the thicker sidewall. it shouldnt throw ur speedo off that much

 

[mr cribb]

best tool I can help you with is from another website 1010tires dot com

there is a tire size calculator that I have used lots of times for general purpose and the occasional boredom.

It's pretty self explanatory when you click on tire size calculator link.

hope this is helpful.

 

[mr cribb]

I went to the website to speed this up even more. By inputting your request your speedometer would be off by 2.1 mph.

The general guideline is that you want to stay within 3% of the original tire diameter any more than this can lead to brake failure.

Your combination you asked about is a whopping 3.16% difference. And as I said earlier by running the 245 75 16 combo, your speedo would be off by 2.1 mph.

I got all this from the website/link I posted earlier. Good luck.

 

[Anime]

Brake failure? What the heck?

Increasing the tire diameter won't cause brake failure, but larger tires do put lots more demand on the stock brakes, so upgrades with much larger tires are usually a mandatory upgrade, but that's about it.

Anyway, going to a ever so slighty higher sidewall from a P235/70R16 to a LT245/75R16 will be just fine. The LT tire will have heavier duty construction and will probably ride a bit firmer, but it'll be a nice real truck tire. The speedo will be slighty off for the first 20,000 miles or so, but as the tread wears down, it'll come within the stock size range and be back to normal. Just watch your speed more carefully and it should be ok, or get a GPS to know for sure.

 

[FIND]

Brake failure? What the heck?

Increasing the tire diameter won't cause brake failure, but larger tires do put lots more demand on the stock brakes, so upgrades with much larger tires are usually a mandatory upgrade, but that's about it.

Anyway, going to a ever so slighty higher sidewall from a P235/70R16 to a LT245/75R16 will be just fine. The LT tire will have heavier duty construction and will probably ride a bit firmer, but it'll be a nice real truck tire. The speedo will be slighty off for the first 20,000 miles or so, but as the tread wears down, it'll come within the stock size range and be back to normal. Just watch your speed more carefully and it should be ok, or get a GPS to know for sure.

+1

Brake failure.....

Many explorer owners on this site upgrade to 31" or 33" tires.... 235/75r15 have an overall height of 29.5 inches, meaning that anything more than 30.4" is more than 3% larger.... No brake failure coming from larger tires.... I could see them recommending no more than 3% larger for speedo accuracy, but yeah.... The only change brought on by going to larger tires is the larger rotational inertia, but, you could easily replicate the additional inertia from going to larger diameter by using a stiffer heavier tire, such as an 8 ply compared to a standard passenger tire. Plenty of people put 10 ply tires on their pickups... no brake failure coming from heavier tires.

Anyways... the people on that site are obviously retarded. Sure, there is some loss of braking efficiency by going to a larger tire.... but brake failure? That would take quite a big difference in tire size or some seriously weak brakes to begin with.

 

[mr cribb]

Look I'm not saying I agree with the statement, I just typed what I read by plugging in the two sizes.

At 3.16% I seriously doubt there'd too much of an issue braking....now say it was 10% or more difference maybe I could see the point.

I have 30x9.50/15 on my X....it's 2wd and supposed to have 225 70 15....According to the calculator it's a difference of 8.64% I have ZERO issues braking...is my speedo off? YUP by 5 mph I just make the speedo read 5mph faster to meet speed limit.

Realistically the only reason I like the calculator is to see how far off the speedometer is going to be. That's how I knew my x's speedo was off.

 

[That911guy]

I thought i read somewhere that you can go in and change the numbers and get an accurate reading on the speedo. Changing something in the chip or similar. Any credibility there?

 

[Anime]

You can change the speedo gear in the transmission/transfer case on models so equipped, usually there's one gear that will work better than another, even if it's still not completely accurate.

It is possible to re-calibrate the speedometers as well, especially on the newer electronic models. Sometimes this requires a trip to the dealer, but there are plenty of plug-in ECU readers and power programmers that will do it as well. Some performance chips, especially of the programmable kind, also allow this, though it may be something you have to get done by whoevers making the tune if it's of the kind you have to keep paying someone else to change.