I was washing my car today and noticed that the rear right tire was 245/45/18, I thought they were all 225/45/18. So checked them all only to find out that one tire is bigger.

Basically I have one tire on my car that is 20 mm wider then the rest, apart from that they are all the same make, spec with similar wear.

I am rather puzzled about how anyone could fit one tire that is the wrong size. There is a scuff on that rim so I wonder if the tire was damaged and replaced by someone with learning/reading difficulties.

Can anyone tell me if I need to get the tires replaced, I would like to just live with it as they have plenty of tread left. Saying that I don't want it to damage the car from being unbalanced or affect the handling.

 

You can get away with mounting any tire size as long as the circumference is roughly within 3% of the others so as not to throw off the DSC.

You can just change 2 of the tires and mount both front or rear or change all 4 to new ones.

 

Well the 245 is going to be slightly taller diameter that 225. Using a tire calculator about 0.7 inches taller?

The general rule is not to use mismatch tires on your drive wheels especially if you have a limited-slip differential. In theory your differential gears will always be working since the tires are different sizes. You could mount the mismatch tires to the front, but wouldn't that cause a pull to one side?

Sounds like previous owner had a flat and the tire shop probably put the closest tire they had in stock.

-Jack

 

Get it changed as soon as you can . It will affect DSC dramatically when you take any corner at speed .

 

EEEEKKKK! get it changed!

 

thanks for the info guys I think the first thing to do is put the bigger tire on the front of the car then change both front tires when I get paid.
I went auto-crossing 2 weeks ago for the first time and didn't know about the tire, i have a good excuse as to why I wasn't faster now

 

The next question is what are the best tires do I buy for max grip for your $$$?

I have just started auto-crossing so want a tire that is super sticky, I was recommended the Dunlop Direzza Sport Z1 Star Spec which look like a great tire for the price. The wheels are 18"x8" how wide can I go for the tires. Obviously 245/45/18 fits on the rim so I would like to go to that width at least, or could I realistically go wider. 2 types of tire are 245/45/18 and 245/40/18 would I be better off getting the lower profile tire for better handling.

Thanks again for your help guys

 

245 is the widest you want to go on an 8" rim and 40 profile is closest to what the stock tyre size is so go with that .

 

And its not good for your diff. to have different sized tires on the rear.

 

I rotated all the tires today front to back and the car is running much better now the rear tires are the same size. I went to tires plus and get a new set of tires Dunlop Direzza Sport Z1 Star Spec. The guy on the desk spent 1 minute looking at his computer and said I can't find them and made no further attempt to try. I don't get it I am just about to spend about $1,000 with the tracking and he can't be bothered to find a solution, so I left and won't be going back... ever.

Being new to the US from the other side of the pond I was wondering if anyone can recommend a good quality garage (Sarasota area) that don't charge dealer prices and are capable of doing some basic mods.