what can I expect going 265 to 285 tires ?

pastor scott.com · December 25, 2006

just a few questions; if i go to 285 tires from factory 265 what problems will I incounter ?

1) will I loose take off power ?

2) will my anti lock brakes system give me trouble ?

3) will I get check engine light ?

and what ever else might happen.

I thought about the auto 4x4 setting since its based on rear wheel slip[age to engauge will it slow its reaction time ?

sorry to ask so many questions. just dont want to spend the buck and then

add more head eachthen I need.

Scott

J45p3r · December 26, 2006

1) Yes

2) No

3) No

Basically installing larger tires has the effect of installing a lower (numerically) gear in the rear. So it'd be like going from a 4.11 gear to a 3.73 (hypothetically). On top of that you also have additional weight which will also rob some power and fuel mileage.

Only other issue will be the speedo will read slow by a few percent unless you get the computer reprogrammed for the change (good excuse for a custom tune?)

pastor scott.com · December 26, 2006

Thanks

I see you have the 285's, how was the stoping changed ?

would you say you really felt the loss in power or just a little ?

Scott

pastor scott.com · December 26, 2006

also I forgot. did the tires hit or did you need to cut some wheel well away ?

sorry

J45p3r · December 26, 2006

I didn't notice a lot of change in stopping, some, but not a lot. I definitely noticed a change off the line, that was very noticeable. I also lost about 1.5 MPG. I did regain some of that with a custom tune though.

No trimming required. The truck now has about a 1.5" T-Bar crank, but I ran the truck for a few months with the 285s and no crank and it never rubbed then, either.

lesZ71 · June 24, 2007

I am going through the 265 vs. 285 debate right now and came across this post. I have a 2004 Z71 with stock 265/70/17 tires (3.73 rear end). I have measured with the stock tires turned to full left and full right and believe that I have enough clearance to easily accomodate the extra 1.1 or so inches for the 285s without doing any torsion bar cranking. I have a some questions that I would like to add to the original post above...

1. Is sidewall flex a problem with the 285s on the stock rim?

2. Will there be a problem should I need to use the spare tire (265)?

3. Other than looking better, is there any real advantage to going with the 285s?

4. Has anyone regretted opting for the 285s over the 265s?

VMax2007 · June 24, 2007

I am going through the 265 vs. 285 debate right now and came across this post. I have a 2004 Z71 with stock 265/70/17 tires (3.73 rear end). I have measured with the stock tires turned to full left and full right and believe that I have enough clearance to easily accomodate the extra 1.1 or so inches for the 285s without doing any torsion bar cranking. I have a some questions that I would like to add to the original post above...

1. Is sidewall flex a problem with the 285s on the stock rim?

2. Will there be a problem should I need to use the spare tire (265)?

3. Other than looking better, is there any real advantage to going with the 285s?

4. Has anyone regretted opting for the 285s over the 265s?

MY .02 worth...

On my 2000 GMC Sierra Z71 I sold a few months ago, I went from 265s to 285s. I never noticed any difference in any of the aforementioned issues.

1. They NEVER rubbed.

2. Theoretically, my speedo should have been off by about 10%, but I only noticed about 2-3 mph discrepency at 65-70 mph.

3. I never noticed any MPG change.

4. Ride was a little softer, but still handled fine.

No regrets!!! I say "Go for it"!!!

lesZ71 · June 24, 2007

So, you did not notice any difference in accelerating from a dead stop or throttle response in general? Thanks for the feedback!

hotwheels57 · June 24, 2007

This site will give you the % change in the speedometer reading (scroll to the bottom)...plug in oem tire size and then new tire size. It'll give you all aspect ratios of both size tires.

http://www.miata.net/garage/tirecalc.html

lesZ71 · June 24, 2007

Thanks! I will give that site a look. I can't really imagine that there would be any noticeable difference in acceleration, transmission shifting, braking, etc....I have a little time before I buy and figured I would get some input from others on this subject. Doing the math, the new effective gear ratio should be around 3.60 instead of the stock 3.73.

265 -> 31.62inches

285 -> 32.72 inches

31.62/32.72 = 0.967%

so 0.967X3.73 = 3.60

J45p3r · June 24, 2007

I am going through the 265 vs. 285 debate right now and came across this post. I have a 2004 Z71 with stock 265/70/17 tires (3.73 rear end). I have measured with the stock tires turned to full left and full right and believe that I have enough clearance to easily accomodate the extra 1.1 or so inches for the 285s without doing any torsion bar cranking. I have a some questions that I would like to add to the original post above...

1. Is sidewall flex a problem with the 285s on the stock rim?

2. Will there be a problem should I need to use the spare tire (265)?

3. Other than looking better, is there any real advantage to going with the 285s?

4. Has anyone regretted opting for the 285s over the 265s?

1. I haven't had an noticeable issues with this.

2. Only if you have a G80 or other locking type of rear diff. If this is the case, throw the 265 on front if needed.

3. It does look better, most other things will be negatives, except additional clearance, etc.

4. No regrets. I definitely noticed a change off the line. I think this is for two reasons. The 285 BFG AT/KOs were SIGNIFICANTLY heavier than the stock Bridgestone tires and the fact they are about an inch taller.

ctahoe · June 24, 2007

On all my full size Chevy trucks I have put on 285/70R17's, IMO the OE tire quality and size stink for full size trucks, always have, always will. I put them on all 5 stock wheels so that if a spare is needed the difference is not a problem for the Anti-lock brakes, stabilitrac, or the 4 wheel drive transfer case. No cranks needed on t-bars, no spacers needed on coil-overs. I've had sets of BFG TA KO's, I currently have a set of Toyo Open Country AT's and IMO they are at the top of the list. I go with LT-metrics and prefer the ride, the capacity, performance, and the lack of roll a heavier, stiffer tire gives. I also find no drawbacks in going with a heavier tire, there is still plenty of braking, and get up and go. The Toyo's are the first time I've had the vehicles settings changed with a flash, I didn't even ask for them to do it, but other than knowing my MPH are reflected correctly (instead of 3 mph off) I have yet to notice any difference.

lesZ71 · June 24, 2007

I thought of one more question in regard to the 265 vs. 285 debate...will there be any difference in the way the tranny shifts...in other words will the shift points be off an or enough to notice? Thanks for all the feedback...this site is great!

svensk · June 25, 2007

I thought of one more question in regard to the 265 vs. 285 debate...will there be any difference in the way the tranny shifts...in other words will the shift points be off an or enough to notice? Thanks for all the feedback...this site is great!

Yes, you might not like your shift points. But, an aftermarket tune can fix that for you. I went from stock 245/75/16 to 265's and I lost a bit of power and tad bit of milage. Imo- I would rather go back to something closer to 245 on my next set just because I want every last bit of performance.

Is this right? I had 245 stock with 3.73 gear, but do they put the same gear in the z-71 which comes with 265's stock? This is a complete mystery to me...Now did or didn't lose some gearing going to a 265 then?