Sinister95Z

I recently got a flat one night after work. The tire is done for and I need to replace it. I found a really good deal locally for a set (2) tires, but I need to see what risk I will be taking to run these tires.

My specs : 18" Eagle 077's 18X8 (not very wide)

The tires I might possibly purchase are 275 40 18's. I know this is not the ideal tire for these rims due to being very wide. What risk am I taking and what is the worst thing that can happen? I only want to run these tires for a short period of time until I get some light weight drag wheels. Please help me out guys...Can it be done even remotely safe?

69z-28

youll be fine. the sidewall of the tire will be sucked it a bit, however ive seen some much wider crap run on skinnier wheels. for a little while, it will be fine. dont try to peg out your speedo, but youll be fine even for 80mph and normal driving. i run 315s on 9.5" wheels. everyone says NOOOOO! dont do it. ive seen it done before, and working at a tire shop, i feel confident in what is on my car, IMO youll be fine, but some will disagree.

paarman97maro

Well when I was going to get those rims, and looking at 8" rims, everywhere I asked people said NOT to mount an 8" rim on a 275. One of the reasons I went with 8.5".

Buttt I love those rims.

Phate

You are not technically supposed to. Its going to create additional strain on the sidewall of the tire and excess heat, and if you dont know, heat on a street tire is the opposite of what you want.

Will it mount up? Yes.
Is it safe? Maybe.
Would I do it? No.

I would just grab up some 245's.

69z-28

how long is a short period of time i suppose? few weeks? few months? year?

Sinister95Z

At least a couple of months. I need to finish up my Auto conversion and valvetrain upgrade before the funds will be available for the new wheels/tires. I literally drive the car 10-15 minutes a day to and from work and thats it.

203banshee

i always thought that 8.5" was good for 275 ?? i was wrong ! lol

so what tire width goes well with what rim width ?

paarman97maro

8.5 is fine with 275. Thats what Im running. Its probably not the perfect size, but ive been on them for 6 months with no issue.

Phate

If its that short of time, I dont think it would be a problem. Just make sure you dont do much highway, if any.

And banshee, thats a hard question to answer. A 275/45 isnt anything near a 275/55. I'd have to make up or find a list with all of the sizes on there.

First off, if you dont know what the numbers mean on the tire, it wont do you any good.

Everyone knows what the last number means in 215/75/15, the 15 is the size of the wheel. But the two first numbers are aspect ratios, meaning the relationship of the hight and width of a tire. An aspect ratio of 75 means that the tire section is 75% as high as it is wide. And the first number would be millimeters, measuring how wide the tire is.

So, lets keep that last size, 215/75/15.

215mm (width)= 8.50"
6.35" = height
6" = rim

Now, if we make it 215/70/15.

215mm (width) = 8.50"
5.93" = height
6" = rim

Does that make it any clearer?

paarman97maro

Phate

Lol. Its not that hard paar.

Just look at the two numbers and compare the ratio.

69z-28

seriously, that was the most basic explantion you can get paar. lol. the first number is the width in millimeters. however wide the tire is in millimeters, thats the first number. then obviously the last number is the rim size. the middler number is just like phate said, a ratio. for instance, my 315-35-17s are almost the same height as my 275-40-17's in the front. the reason for this is... since the tire is wider, it needs a smaller aspect ratio (35 instead of 40) to come out to the same height in the end.

Sinister95Z

Sounds like I will be fine as I will not be doing ANY highway driving. Should I stay away from the frequent street race? Do I run a chance of the tire blowing off the rim?

Phate

Yes, any major stresses on the tire is not advised. Its going to be much weaker than a typical correctly sized tire would be, and heat up 2x as fast.

paarman97maro

I get it dickslap... I just dont like looking at math problems.