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Im interested to know to. I was looking into coil spring spacers if necessary... Even an extra half inch all around might be enough to fit the next size up
Can we convince you to measure on your car tires to see? I'd be concerned with rear wheel arch chafe, front might clear it even with wheels cranked all the way
The image below is out of my original vehicle manual
It clearly shows the tyre size to be 215 70 R15 which has a large tyre diameter of 26.9 inches. These are readily available and are ideal for front tyres
To get a wider tyre for the rear AND to match the diameter the 245 60 R15 works a treat which are also readily available.
The suggested 225 60 R15 are way too small and you will increase your odometer or your car in no time as the wheels rotate much quicker per mile causing a higher reading on your odometer which potentially has the effect of adding unnecessary miles which may reduce it's value.
The concern, not serious, is that the 6.5" wide original wheels are not really wide enough to properly support a 245/60 tire. They're borderline even for the 235/60 tires. It's not like something horrible will happen but you won't be getting the best out of the tire with the sidewalls pinched-in on a too-narrow wheel. A 245 would work better on a 7.5-8.0" wide wheel.
But, you'll still have the look you want with wider tires
The suggested 225 60 R15 are way too small and you will increase your odometer or your car in no time as the wheels rotate much quicker per mile causing a higher reading on your odometer which potentially has the effect of adding unnecessary miles which may reduce it's value.
On my XJS it amounted to about a 3% or 4% difference. This will vary from car-to-car in accordance with the inevitable speedometer error which every car has to some degree or another
Ok so in the last week I have been running 225/60R15 on the rear for about 2 days and noticed a MASSIVE difference in the vehicle handling from the original tyres which were also incorrect but slightly larger diameter than the 225 tyres.
I noticed the rear of the car started to dive into the corners quite aggressively as if the car had been installed with 4 wheel steering or as if the rear shocks or springs had softened.
I tested this throroughy on high speed corners on my local highway and to be honest I didn't like it at all. It was a little scary as if the rear was going to drop out and let go.
So, I went back to my tyre guy and installed the correct factory 215/70R15 and the difference was incredible. MUCH more control in the rear with no more diving into corners.
See below. Hankook 225's on the left and the Goodride 215's on the right. (Big difference in overall diameter - 1.3 inches to be precise or 33mm).
IMO stick to the factory size tyre of 215/70R15!
Last edited by Crackerbuzz; 10-02-2018 at 01:14 PM.
Ok so in the last week I have been running 225/60R15 on the rear for about 2 days and noticed a MASSIVE difference in the vehicle handling from the original tyres which were also incorrect but slightly larger diameter than the 225 tyres.
What size and brand were you running on the front? If different size and type, that might account for odd results.
But, beyond a possible front-rear mismatch, it might well come down to the tire design more than the size. Lots of different brands and designs in that size and surely they have different characteristics.
FWIW, I had no negative consequences going from 215/70 to 225/60.
What size and brand were you running on the front? If different size and type, that might account for odd results.
But, beyond a possible front-rear mismatch, it might well come down to the tire design more than the size. Lots of different brands and designs in that size and surely they have different characteristics.
FWIW, I had no negative consequences going from 215/70 to 225/60.
Cheers
DD
Hey Doug,
Front is running 215/65R15 which I haven't changed. Interesting you didn't notice a difference going from 215/70. Maybe the brand makes a difference.
The 225's I bought were Hankook so should have been ok. I have replaced them with 215/70 Goodrides which are now what is on the rear of the car.
Drives great now. (Fronts are also Goodrides but 65 profile instead of 70 profile)
The rear was also running 215/65 when I bought the car prior to trying the 225's and changing to 215/70
my xjs had a factory 235 60 15. witch is the size im currently using. i have mostly come to the conclusion that i need to get away from a 15 inch rim to get a better tire. at 400 horsepower i already have traction issues. tread compound is just as important if not more so than tire width. there is a huge lack of tire choices in the 235 tire size basically your choices are a all season m/s tire or a more dedicated drag radial. i love my factory rims and don't want to change them. factory rim width is already borderline too narrow for a 235 tire. from what i can see the same availability problem in the 245/60/15 size. i would love to see someone come out with a sticker summer performance size tire that would work without going to a narrower
my xjs had a factory 235 60 15. witch is the size im currently using. i have mostly come to the conclusion that i need to get away from a 15 inch rim to get a better tire. at 400 horsepower i already have traction issues. tread compound is just as important if not more so than tire width. there is a huge lack of tire choices in the 235 tire size basically your choices are a all season m/s tire or a more dedicated drag radial. i love my factory rims and don't want to change them. factory rim width is already borderline too narrow for a 235 tire. from what i can see the same availability problem in the 245/60/15 size. i would love to see someone come out with a sticker summer performance size tire that would work without going to a narrower
I was gunna say how did you manage 400hp but then saw you had a SBC.
Would love that power, but gotta keep my 12 until it dies.
its like having tea and crumpets smothered in Jack Daniels. when i bought my car i wanted a v12 now im glad i ended up with a 6 because the chevy power would spank even a v12 and i feel less guilty about swapping a 6cyl car. did my swap because i was having problems with the original powertrain and ultimately i wanted more power i don't regret it one bit. very soon its getting a supercharger should bump me up over 500hp
of course thats not going to help my traction problems at all...lol.
hoosier makes some dot street drag radials in 235 60 15 but i really wish i could find more of a autocross type tire in that size. like a falkin azenis or similar.
its like having tea and crumpets smothered in Jack Daniels. when i bought my car i wanted a v12 now im glad i ended up with a 6 because the chevy power would spank even a v12 and i feel less guilty about swapping a 6cyl car. did my swap because i was having problems with the original powertrain and ultimately i wanted more power i don't regret it one bit. very soon its getting a supercharger should bump me up over 500hp
of course thats not going to help my traction problems at all...lol.
hoosier makes some dot street drag radials in 235 60 15 but i really wish i could find more of a autocross type tire in that size. like a falkin azenis or similar.
Love the analogy. Tea & crumpets smothered in Jack Daniels. Nice!
Magnusun SC? That will keep it low under the hood and boost lots of power.
wrong kind of traction....lol unless you are driving your xjs in the snow or offroad. less tread groves with a shallow tread more contact patch and a soft rubber is what you want for maximum traction in dry conditions witch is when i think most people drive there jags. some may want a all season tire that is better in the rain but i don't think many are looking for all terrain tires for there jags..... well i guess you never know.
Originally Posted by Crackerbuzz
Love the analogy. Tea & crumpets smothered in Jack Daniels. Nice!
Magnusun SC? That will keep it low under the hood and boost lots of power.
Craig
small cased wieand roots style blower, its not going to fit under the hood a performance dual plane intake/carb hardly fits under the hood im thinking i am a bit sad its going to loose its factory appearance but anyone that knows much about cars picks up on the sound of a healthy small block anyway. i think its still going to look good going to top it off with a hillborn style scoop. im sure many here will disagree though.
09-28-2018, 05:21 PM
