285/70/16 - RPM/Gearing/Longevity Questions

[levee-11]

Hi all, I'm planning on getting some 285/70/16s for the 4Runner and had some questions.

First off, is this gonna put a huge load on my transmission, and is it gonna hurt the longevity of my runner? I got 230k miles most of which I believe are highway miles, and the engine was meticulously taken care of before I bought it about a year ago (I mean I've never seen anyone put that much care into a vehicle, PO was very good owner) so my engine and tranny are in very good health, but should I expect my runner to not last as long as a stock one, especially if I'm using it as my daily and my off-roader? For anyone that has these tires, how many miles do you have, and how long have you had them?

Second. I don't know my overdrive gearing ratio as I believe there were several gearing ratios for the OD over the span of the third gens, but I have 4.10 Differential gear ratio (and yes I know gear ratio for differential won't affect RPM, but I say this so you know when answering about the get up and go speed) but as of now with my stock 265/70/16s I have 2000RPM at 60mph and 2500RPM at 70mph. I am going to notice a huge spike in RPM needed to like take off from a light at the same speed I normally would? I don't like going over 3k as I never normally have to go above 2.5k to have decent take off (Not a grandma driver, just don't like to rev the balls out of the runner and I've never really needed to go above 2.5k to climb speed quickly). And what RPM should I expect at 60 and 70mph?

Lastly, Should I re-gear my diff for these tires? They would be just under 33s, and to my understanding the 4Runners don't need to be re-geared to wear 33s. And since my speed will be a little off on the speedometer, is there any kit I can get to have a properly geared speed measuring gear for these tires (might be a dumb question, not too knowledgable on how this works)

Thanks for taking the time to read, correct me if I said anything stupid, responses would be amazing, and would defiantly help me choose between 285s or some form of a 275.

 

[Bad Luck]

Hi all, I'm planning on getting some 285/70/16s for the 4Runner and had some questions.

First off, is this gonna put a huge load on my transmission, and is it gonna hurt the longevity of my runner? I got 230k miles most of which I believe are highway miles, and the engine was meticulously taken care of before I bought it about a year ago (I mean I've never seen anyone put that much care into a vehicle, PO was very good owner) so my engine and tranny are in very good health, but should I expect my runner to not last as long as a stock one, especially if I'm using it as my daily and my off-roader? For anyone that has these tires, how many miles do you have, and how long have you had them?

Second. I don't know my overdrive gearing ratio as I believe there were several gearing ratios for the OD over the span of the third gens, but I have 4.10 Differential gear ratio (and yes I know gear ratio for differential won't affect RPM, but I say this so you know when answering about the get up and go speed) but as of now with my stock 265/70/16s I have 2000RPM at 60mph and 2500RPM at 70mph. I am going to notice a huge spike in RPM needed to like take off from a light at the same speed I normally would? I don't like going over 3k as I never normally have to go above 2.5k to have decent take off (Not a grandma driver, just don't like to rev the balls out of the runner and I've never really needed to go above 2.5k to climb speed quickly). And what RPM should I expect at 60 and 70mph?

Lastly, Should I re-gear my diff for these tires? They would be just under 33s, and to my understanding the 4Runners don't need to be re-geared to wear 33s. And since my speed will be a little off on the speedometer, is there any kit I can get to have a properly geared speed measuring gear for these tires (might be a dumb question, not too knowledgable on how this works)

Thanks for taking the time to read, correct me if I said anything stupid, responses would be amazing, and would defiantly help me choose between 285s or some form of a 275.

I think you mean 285/75R16's. Those are almost a 33 inch tall tire. 285/70R16's are 31.7 inches. There's a lot of folks running stock gears with that size tire. It will be a little more sluggish, but driving experience will really depend on your terrain. The more hilly it is the more you will notice. If you want to see your rpm changes with different tires I suggest using this calculator: Gear Ratio Calculator You have an a340f transmission and use the "Toyota Tacoma and FJ" transfer case option to get the correct low range ratio. Your speedo will be off and you can either know what percentage it will be off and live with it or use a speedometer correction box. I believe phattyduck has instructions on how he did his in his build thread if I remember correctly. It's a dakota digital product.

FYI all 3rd gen 4Runner's automatics have the same transmission ratios.

To compare tire sizes I use this calculator: Tire Size Comparison

 

[Hopeless Diamond]

Keep up with all the maintenance, don't drive it like it's a Porsche, and you'll be fine. 355k here, lifted with 33's, too much weight (me and the 4R) and getting more all the time (me and the 4R). I go over Snoqualmie and Blewett all the time, constantly use it in the back-country. No worries.

Turn off the OD going up passes. Use 4lo even on simple roads, it will make a huge difference in trans temps, fuel will suffer but that's a small price for keeping your trans longer.

Before you spend money on re-gearing, make sure you take care of the important things, LBJs, radiator, timing belts, etc. If you're not sure of the providence of those items, develop a plan to change them out sooner than later (using OEM). Knowing they're fresh and good will give you a lot of peace of mind and will keep that vehicle lasting.

 

[Cree]

You'll be looking at about 7% reduction in effective final drive ratio, so you'll feel like you have 3.90s. Not a terrible gear set, but not the best for your power band either. What will probably make more of a noticeable difference is what Load Range your tire is. The weight difference between a Load C and a Load E is not insignificant when talking about unsprung rotational mass.

I can't tell the difference between my old 265 16's and my 285 17's, but I went from an P rated at 41lbs to a Load C at 50, so the weight difference was minimal. Going from the P rated to the same 285 in a Load E is almost 20lbs difference, per tire. FFT.

 

[spartacus]

33 inch tires won't hurt the motor and Trans with proper maintenance. It will effect the front suspension cooponents and CV axles while off roading. There will be a some loss in power and braking and there will be a lot more downshifting without regear. With 33's you'll need pan hard correction kit. longer brake lines. off road skid plates sliders etc more weight.
Some have slapped on 33 and have learned to live with it others have spent a considerable amount of money, effort and have built proper off road rigs lots of build threads.
Go off road in your stock truck will handle level 3 trails pretty well then go from there.

 

[deves2]

You didn't specify why you wanted to go with 285's. I wanted a 33 inch tire and went with 255 85 16 and really liked them. I have also run the 285's but due to the extra weight of the 285's my acceleration was terrible, gas mileage sucked, climbing a mountain(I live in the mountains) was constantly changing gears and I had to modify the pinch welds and add wheel spacers to keep it from rubbing. I generally thought the 285's were ok but the 255's were great in comparison. Note that I also offroad a lot and the 255's also worked great.. just my 2 cents.

 

[levee-11]

I think you mean 285/75R16's. Those are almost a 33 inch tall tire. 285/70R16's are 31.7 inches. There's a lot of folks running stock gears with that size tire. It will be a little more sluggish, but driving experience will really depend on your terrain. The more hilly it is the more you will notice. If you want to see your rpm changes with different tires I suggest using this calculator: Gear Ratio Calculator You have an a340f transmission and use the "Toyota Tacoma and FJ" transfer case option to get the correct low range ratio. Your speedo will be off and you can either know what percentage it will be off and live with it or use a speedometer correction box. I believe phattyduck has instructions on how he did his in his build thread if I remember correctly. It's a dakota digital product.

FYI all 3rd gen 4Runner's automatics have the same transmission ratios.

To compare tire sizes I use this calculator: Tire Size Comparison

Thanks for the info. I initially meant the 285/70/16s but after your reply realized I was wrong, and yes I would go with the 75s. I will check out phattyduck's thread.

 

[levee-11]

You didn't specify why you wanted to go with 285's. I wanted a 33 inch tire and went with 255 85 16 and really liked them. I have also run the 285's but due to the extra weight of the 285's my acceleration was terrible, gas mileage sucked, climbing a mountain(I live in the mountains) was constantly changing gears and I had to modify the pinch welds and add wheel spacers to keep it from rubbing. I generally thought the 285's were ok but the 255's were great in comparison. Note that I also offroad a lot and the 255's also worked great.. just my 2 cents.

Thank you. I wanted the 285s because I wanted the wider stance to accommodate the loss in the center of gravity from the 3 inch lift I'm planning. I will check out the 255s. Does your truck feel tipsy with the skinny tires, and do they rub?