Guise - I need some help with tires

[SSSnail]

This.

You'll get way better specific advise at a car model specific forum. I know for both my vehicles (evo x / corvette) I can find hundreds of different posts about rim / tire sizing, offsets, etc...

What sort of car is this going on? bimmer?

225/40/19 and 255/35/19 are almost identical in overall diameter. You shouldn't have any issues swapping the 255's on the front (besides a bit more push... nothing a bit more rsb can't fix). As at least one poster above said... you will have to look at:

1. How much clearance do you have from the inside of the rim to the suspension

2. How much clearance do you have from the outside of the tire to the fender

3. How much clearance do you have from the inside of the tire to the fender well / lining (these are often easy to modify)

4. If you have large brakes, you'll have to ensure that your new wheels will clear the calipers. Note that not all rims of a given size are created equal (spoke design and offset are important).

Thanks mate. I did a lot of searching, but couldn't find the definitive answers on my two questions in the OP. 225/40/19 fronts and 255/35/19 rears are OEM. Being that these are RFTs, I thought if I go to 255/40/19 would give me a bit better ride. But since this is the garage, I'm also curious on what's the highest ratio I can safely go to without throwing everything out of whack.

But JLee gave the best and simplest answers, which I'm surprised I didn't just do it myself, which is toss the rear tires on the front and move them about to see how they fit and how much clearance I have.

 

[tortillasoup]

This here tells you that I know enough about the effects of wider tires in front. And merely asking if there's anything else I should worry about, which JLee (again, thank you - you're the only smart guy that posted answers in this thread so far) addressed.

Wasn't this your first question?

What's the highest height ratio I can go without getting out of speedometer and safety specs?

With a question like that, it would imply that you should be able to calculate it yourself to figure out what tire combination you could have that would keep your speedometer accurate. As for safety, aside from sanctioned tire/wheel sizes both officially and unofficially, you'd have to figure that out yourself.

 

[SSSnail]

Wasn't this your first question?


With a question like that, it would imply that you should be able to calculate it yourself to figure out what tire combination you could have that would keep your speedometer accurate. As for safety, aside from sanctioned tire/wheel sizes both officially and unofficially, you'd have to figure that out yourself.

Yes it was, and it'd be awesome if people would just answer the question. Perhaps I should have given a % tolerance, as in an acceptable deviation. My bad.

 

[tortillasoup]

Yes it was, and it'd be awesome if people would just answer the question. Perhaps I should have given a % tolerance, as in an acceptable deviation. My bad.

Well if you do the math, you'd see that a size difference like that is quite a big difference. What % tolerance is acceptable is up to you. I wouldn't tolerate more than 5% difference. The only way to truly find out is to use a GPS and measure your actual speed and readout speed and see if it's acceptable to you.

 

[jlee]

Thanks mate. I did a lot of searching, but couldn't find the definitive answers on my two questions in the OP. 225/40/19 fronts and 255/35/19 rears are OEM. Being that these are RFTs, I thought if I go to 255/40/19 would give me a bit better ride. But since this is the garage, I'm also curious on what's the highest ratio I can safely go to without throwing everything out of whack.

But JLee gave the best and simplest answers, which I'm surprised I didn't just do it myself, which is toss the rear tires on the front and move them about to see how they fit and how much clearance I have.

As far as safety is concerned (stability control, traction control, ABS) as long as all tires are the same circumference it won't matter. I ran 315/75R16's on my 80 series landcruiser with stock gears (35" tire vs stock 31"). It was slower than shit (and the speedometer was off) but it's not going to hurt anything.